If you’re looking for the weekly Corsi charts, you’ve come to the right place. Incidentally, they aren’t here, so you’re also in the wrong place. It’s not you, it’s me.
I’ve been busy finishing up work on my thesis, an additional research paper, and other assorted family things (hence the gap between posts), but I haven’t been completely ignoring hockey. I try to find as much to read about advanced hockey statistics as possible, and I ran across an article on the Maple Leafs’ SBN blog that caused something of a crisis of conscience.
The last two columns are the r-value for even strength Corsi and the R2 value as it relates to winning percentage. The first column to the right of 5v5CF% is the R^2 value over six years of statistics that the folks at Pension Plan Puppets collected. Their analysis indicated that Corsi is both highly replicable and relatively highly correlated with winning percentage.
Visualizing r^2, via BMG Lab Tech
Having said that, I’ve decided to shelve the Corsi project for now. It may be true that Corsi is related to winning percentage, but B1G hockey is starting and I wrote back in my first Corsi post that I’d start doing goal-by-goal analysis posts again at this point. I decided to stop tracking Corsi data because I only have a limited amount of free time to pour into this each week, and if I’m going to spend 5-8 hours a week analyzing Michigan hockey then I think most people would rather see GBGA than something that may be highly correlated with winning but has very little aesthetic appeal. If you’ve been using my Corsi posts in place of Ambien then I’m glad I had the opportunity to both inform you and put you to sleep. I’ll try and get back to Corsi at some point, but I can’t make any promises.
If you’re now wondering what GBGA is then I think I’d describe it as a Picture Pages/UFR hybrid. I break down every goal for and against, hoping to explain what happened in a sport where important things happen in tenths of seconds and add something entertaining/informative to the world of Michigan hockey.
2:51- OSU 0 Michigan 1: Lynch from Kile & Allen
Michigan gets the puck in deep and Lynch goes to carry it behind the net. The two OSU defensemen should follow the routes drawn out on the screen shot; as one goes to cover Lynch on the wraparound, the other should go to the front of the net.
Instead, the right defenseman follows Lynch behind the net. This vacates the front of the net, which comes into play later. The left D has no choice but to leave Lynch and follow the pass to Kile.
A simple pass from Kile to Lynch puts the puck in a dangerous spot for OSU. Since the right D followed Lynch behind the net there’s no one to protect the net-front area. Lynch is going to get an easy wrap around shot. Look at how deep the OSU goaltender is in his net. He’ got the post locked down, but he’s still standing when Lynch gets the puck on his stick and you can see how open to five hole area is. Lynch puts this one away for Michigan’s first B1G conference goal.
15:46- OSU 1 Michigan 1: PPG Dzingel from McCormick & Szczechura
Michigan’s box is shifted far left. You can see that OSU has three players in the frame, which means that two are off screen and essentially undefended.
Motte makes a mistake and tries to block the shot in the slot. This really could fall to the defender in the front of the net, as Motte’s assignment is to cover the far right (where the arrow’s pointing, naturally).
Pretty obvious that this mistake leads to a really, really wide open shot. The goal itself was soft, as it just sort of rolls over Nagelvoort’s glove but the defensive breakdown is still key to this goal.
6:41- OSU 1 Michigan 2: PPG Compher from Moffatt & Guptill
The key here is that the top of OSU’s box has sagged down into the slot instead of staying high to cover the point. This allows Michigan to pass across the zone from the boards.
Moffatt takes the shot that’s there for him. It’s not a bad shot, but it’s not exactly a high percentage shot. The best case scenario is what happens, which is a big, uncleared rebound in front. The beauty of the power play is that Compher (circled above) is going to be undefended if the low defensemen doesn’t get there in time.
While it doesn’t quite work out the way I noted above, it still works out. The Michigan player essentially sets a pick, leaving Compher to backhand the puck into the really, really open half of the net. Also, OSU’s goalie Logan Davis is like whoa slow laterally.
HIGH FIVE METAL BARS I FEEL YOU
14:26- OSU 2 Michigan 2: PPG McCormick from Szczechura & Fritz
DeBlois takes away the passing lane to the blueline, so OSU works the puck down low.
Bennett tries to take away the pass to the slot but is about a half second too late, and the puck gets tipped through Nagelvoort’s legs.
19:43- OSU 2 Michigan 3: Guptill from Compher
Compher wins the faceoff, which is huge. Even more important, however, is that DeBlois is able to tie his man up. This allows a clean tap across from Compher to Guptill…
...and a very, very clean shot from Guptill. He lifts the puck perfectly, hitting the top corner before Davis knows what (didn’t) hit him.
16:47- OSU 3 Michigan 3: Greco from Fritz
Credit where credit’s due, OSU’s forechecking creates this goal. Michigan makes a bad decision to play the puck back, and there’s no Michigan skater to collect the weak pass. OSU gets there first and gains possession.
No one notices the skater in the slot until it’s too late; Downing was behind the net and doesn’t cover the front fast enough, Motte can’t catch him either, and Nagelvoort (who was locking down the post) can’t stop the wide-open slot.
Michigan’s offense-turned-defense on this play.
3:38- OSU 3 Michigan 4: Copp from Bennett & De Jong
Mac Bennett, man. He sees a huge passing lane and puts a perfect pass….
…on the stick of Andrew Copp.
He gathers, shoots, scores, and then this.
<a href="http://imgur.com/JkqGMww"> Limited numbers of posters of, and signed by, Rick Leach, Russell Davis, and Harlan Huckleby, available starting at 10:30 a.m. For the cause of fixing up the house of a boy with a debilitating illness, there is a 401(c)(3) set up, so donations are tax deductible. The location is outside the house next to the M Go Patio, closer to the stadium. Address: 310 Berkley, a/k/a Wolverine Little House next to the old AAA parking lot which is now just landscaped. We have been raising funds at each home game, and hope to go over the top today. picture from the Little House looking towards the Big House:
Thank you for the kind words last week and hopefully you're having a wonderful long holiday weekend! Low pressure moving through Canada and across Lake Superior will bring a warm front through the area Saturday. With high pressure pushing eastward, the pressure gradient will increase between the systems - creating a bit of a southerly breeze. It will be a great end-of-November football day, with afternoon temps near 40 with the sunshine!
Up and at em early to get that awesome tailgating spot for this big game! You'll definitely want the heavier coat and hot coffee at this one! We'll have some high clouds to start the day, with temperatures in the mid 20s through mid-morning. Winds will be out of the SE at 10mph (leaves rustle, blow about), but begin to become more southerly towards 10am. It's not much of a wind, but brrr it will give us a wind chill in the teens. As the warmer air makes it's way in, expect temperatures to go up and cloud cover to go down heading towards kickoff.
36 degrees for the start of the game! Hopefully you layered up - temps will continue to rise throughout the first half, but it isn't exactly going to feel tropical with a wind chill in the mid 20s! Hopefully you also kept the sunglasses handy because we'll see some clouds, but a decent amount of sun too. Winds will be out of the south at 10-15mph for the first half (paper blows about, small branches sway).
Warming trend continues, and we'll be up to a balmy 39 degrees for the halftime snack (hot chocolate?) break. It will still feel like 30 thanks to the breeze. Winds have shifted slightly to be out of the SSW, still up around 12mph. Still plenty of sun, but many of those clouds stick around too.
Hitting the afternoon high as you're leaving the game - at 41 degrees. A mix of sun and clouds with SSW winds dropping to about 10mph as you're headed out for a downtown dinner! As the sun sets the cloud cover will increase, and we'll become mostly cloudy for the rest of the evening and overnight. Temps will drop to 32 for dinner, and remain right around 30 until last call. Stay bundled up if you're going out late - that wind is light (about 5mph out of the SW), but it's still going to create a wind chill in the 20s. Beat. Ohio.
Christina Burkhart is a meteorologist for NBC/ABC in Traverse City, MI. She grew up in Ann Arbor and associates Saturdays with Michigan football. Go Blue!!
'Tis this season:
Saturday, December 7 is that annual charity event I help coordinate and MGoBlog readers have helped keep alive. Each year in early December we go to a couple of homeless shelters and throw the kids in there a giant Christmas party. There's photos with Santa, games, dancing, arts & crafts, nail painting, food, etc. Then while the young 'uns are distracted, their parents "shop" for gifts for them in a "gift store" filled with donated new toys and stuff, a goodly portion of which MGoReaders sent from Amazon. Then everyone comes together for pizza and cake and dancing.
We call it "Adopt a Shelter." There are two sites:
- Salvation Army's Denby Center (formerly the Booth Evangeline Center). A big party run by Mitch Albom's Time to Help organization (one I'm at). Key person is Rachel Williams.
- Genesis II House. A great women and children's shelter where Julie has kept the event going.
My involvement is closer with the former. For the latter Julie needs about 20 volunteers, each who bring gift donations. Hers is a bit more low-key. Email Julie if you want to volunteer there [UPDATE 12/2: They still need about 7 more volunteers). As for the Denby Center one, a bit more detail:
Stocking the Store
We need gifts.
Gift donations should be unwrapped, tasteful, and between $15-$20. Stuff that needs batteries should come with batteries. No guns, no swords, no violent comic books. Historically we tend to fall short with stuff for young moms.
AGE RANGE: The age of the children range from 9 months to 16 years old. Here's the numbers the shelter expected to have as of this week:
Age of Residents Boys Girls Age 0-2 10 11 Age 3-5 5 5 Age 6-10 5 10 Age 11-14 6 5 Age 15-17 - 6 Adults (Age 19-68) - 67
- SIZES: A variety of sizes ranging from newborn to 3X are needed. The larger sizes (2X and 3X are for girls.)
- TOYS: Age-appropriate toys and educational toys are needed.
- CLOTHES: Winter in Detroit. Also a reminder that all young adults and teens, no matter their station, care about style. It may seem counterintuitive but one really nice thing is more appreciated than a package of four just-the-thing things.
- TOILETRIES: All types of toiletries are needed, except NOTHING with ALCOHOL in it. Shampoo, Conditioner, Toothpaste, Toothbrushes, Body Lotion, Women’s Deodorant, Body Wash, Soap, Washcloths, Towels.
How much stuff each family gets depends on how much stuff is donated. The remainder is always left to the shelters since they—as you can imagine—have a high turnover. Before March it's all given out.
For the last few years we've found putting up an Amazon Wish List makes it pretty easy—you're welcome to find things not on the list. Gifts are usually $15-$20. But you don't have to use that—for example Moe's is having a 30% off sale today.
Things they asked for specifically: Leap Frog/other learning games, Puzzles, Winter Clothes/Gear (children and women's M, L, and XL especially), Barbies, Super Hero Toys, Legos, Winter Coats, Toy Trucks, Baby Dolls, Adult Pajamas, Clothing and Accessories for Newborns, Baby Strollers for Parents, Brat Dolls, Pants/Leggings, Little People Toys, Board Games, Baby Alive Dolls, Toddler Toys, Books, Hand Soap, Deodorant, Tooth Brushes/Toothpaste, Lotion, Baby Wipes, Diapers, Feminine Products, Socks for Adult Women and Children, Underwear for Adult Women and Children
For donations to the Booth party, send them to Detroit Rescue Ministries (default address on that wish list link) at:
Time to Help Christmas Party
c/o Rachel Williams
150 West Stimson Street
Detroit, MI 48201
Poor Rachel's office is usually just completely stacked with boxes by Friday.
Join us on Saturday, December 7, 2013. One thing you might do is try to pump out 190 photos with Santa from two little portable printers (yes they'll both be working this year—sorry about that). Another is serve bagels. Or man the gift store. Or one lady reader last year came up with the idea of having the kids make picture frames for their Santa photos.
Detroit, MI. 48219
South of 8-mile between Evergreen and Lahser
Set up will begin at 8 a.m., and the party will be open to the residents beginning at 10 a.m. with an ending time of 1 p.m.
The party, which will provide breakfast and lunch to those in attendance, as well as an arts and craft station for children, a manicure and spa room for the mothers, a game center for teens, a store for the mothers to shop for their children and Santa and Mrs. Clause at the end, will need full volunteer support!
We are asking each volunteer to bring at least 1 gift to include in our gift shop. To register for the event go to http://atimetohelp.org/volunteer.htm (it's the only event on the calendar at the moment since the 2014 calendar isn't up yet).
I will have an updated list shortly for what we don't have confirmed, since this has changed since I checked in last. But I believe we still need:
- Breakfast confections (donuts, bagels, orange juice, coffee, fruit, etc.)
- Games for teen game center
- Ice cream and cake
- Arts and crafts materials
- Nail salon artists and nail polish
- Holiday decorations
A Time to Help Coordinator
313-993-4700 ext. 4715
Why Is a Charity on a Sports Blog?
Because I'm involved and I work here, dammit. But some backstory: this event used to be one of two put on by Volunteer Impact (I was a board member of that), which mostly existed to help service organizations find volunteers for their projects, but had a few signature events of its own. This was one of those events.
When we closed down VI, we lost the donor base for this and the other thing. It looked for a time like it would end, until 1) Mitch Albom, through his Time to Help organization, and longtime volunteer Julie Kroflich, stepped up to keep their two sites alive; and 2) Brian let me put up a post on it and MGoBloggers came through, stocking the store with donations and showing up to volunteer. Since then MGoBloggers' donations have been the engine that's kept it going.
The other event was "Hands on Detroit," a Detroit spring cleanup thing that the Ilitch Foundation took over. They meet at Comerica Park on a Saturday and go around making the city look nice for summer.
Can't I Just Give You Money?
Yeah, but give it to the organization putting the event not, not me. If you can't find something on the Amazon lists above, donate to S.A.Y. Detroit, the umbrella organization Time to Help, and specify in the comments that this is for the "Time to Help Christmas Party."
Setting the Scene
no animals were harmed in the making of this diary
Apology. I am sorry to all those who are cringing at seeing another experience diary. I had originally conceived of this as being a two part study, with the first looking at the running game and the second looking at the passing game. Despite the other diaries, both of which were useful in their own ways, I think there is still some horse meat to be gleaned from the carcass of o-line experience as it relates to pass protection. The horse might be dead, but that doesn’t mean it’s useless. Oh, and there's another one since I originally wrote this thing up.
Previous Work. In the first diary, I attempted to demonstrate that o-line experience does indeed play a role in governing a team’s ability to run the ball. R-squared values ranged between about 0.05 and 0.10 depending on how we defined “experience,” suggesting that about 5-10% of the variation in YPC across FBS can be explained by a team’s experience along the o-line. Clearly other factors are also important to running the ball well, but experience isn’t meaningless. Further manipulations to the data set suggested that interior line experience is more important than tackle experience and that the “your line is only as good as its weakest link” argument does hold water.
Some of the comments from that diary questioned why we don’t move one or both of our experienced and talented tackles to the interior if that is where it really seems to matter. Transaction costs of moving around linemen aside, the question is valid in general terms. Why not put your best linemen on the inside if those are the most important positions? A variety of answers could be given to this question – for example, exterior and interior line positions could have different ideal body types with regard to height, weight, strength, and agility – but the most obvious response is that tackles are more influential in the passing game. Our best linemen play at tackle because they protect our quarterback.
Questions. This is a proposition that can be tested statistically, and that’s what I aim to do in the second part of this study. My metric for o-line success in the passing game is sack percentage (i.e., the percentage of pass attempts on which your QB is sacked), since it’s the o-line’s job to keep the QB clean. Using the same essential methodology as the last study, I aim to answer four questions:
- Does o-line experience help prevent sacks?
- Is tackle experience or interior line experience more important in protecting the quarterback?
- Does the “weakest link” theorem hold for the passing game?
- What else could influence sack percentage?
Data. This study looks at 123 FBS teams (Georgia State and UTSA are omitted since their info wasn’t on ESPN). Sack percentage stats come from ESPN, and the experience data comes from the scouting site Ourlads. Star rankings that come at the end of this study are taken from Rivals. Photos come from MGoBlog's flickr account and are attributable to Bryan Fuller. Check out the previous diary for basic definitions of the statistics that are used.
This is long, so buckle up. Feel free to jump to the conclusions if you don’t want the nitty gritty. All the data are summarized in a…chart? Chart.
Questions and Answers
Probably cropped out: massive amounts of backside pressure
Question 1: Does o-line experience help prevent sacks?
Let’s start by taking a broad look using average experience in years of the offensive line. The relationship between experience and sack percentage is plotted below. Click on the graph to see the same sack percentage data plotted against total number of starts. The plot is oriented so that up is good (i.e., your QB isn't getting sacked that often) and down is bad (i.e., you're looking like Michigan against MSU and Nebraska).
Although the trend line makes it look as though there is an inverse relationship between sack percentage and experience (i.e., sacks go down as experience goes up), which is what we’d expect, the r-squared is relatively low (0.02) and the p-value (0.10) suggests the trend may not be statistically significant. If we plot the same relationship but use starts as our metric for experience, the relationship becomes even more spurious with an r-squared of 0.01 and a p-value of 0.28 (click on above graph to see scatter plot). On the whole, total or average o-line experience doesn’t seem to be a great predictor of the o-line’s ability to keep the quarterback from getting sacked.
Question 2: Is tackle experience or interior line experience more important in protecting the quarterback?
I don't care who matters more as long as we keep it under 7 sacks a game
We saw in the previous study that interior line experience was more important to run game success than tackle experience. We’d likely expect the opposite to be true for the passing game based on the premium put on left tackles both in college and in the pros. Average tackle experience and sack percentage is plotted below.
This is unexpected. The correlation is spurious. The r-squared is less than 0.01, and the p-value is 0.67, both of which suggest there is no correlation between tackle experience and sack percentage. The trend line actually rises slightly, which would indicate that sack percentage rises as tackles get more experienced, which makes no sense at all, even if the correlation was statistically significant. On the whole, tackle experience does not appear to be a good predictor of your team’s ability to not give up sacks.
Could the interior of the line be more important in the passing game as well? Click for enlarged scatterplot with teams divided by conference and all BCS teams labeled.
Now we’re getting somewhere. The trend line makes intuitive sense. The percentage of sacks you give up goes down as your interior linemen become more experienced. The r-squared is 0.05, implying interior line experience can explain about 5% of the variance in sack percentage. The p-value is 0.02 suggesting that results are statistically significant. The slope of the trend line suggests that an extra year of average interior line experience is worth a drop of almost 1 percent in sack percentage. If you extrapolate that over the course of a season, that’s about 3 to 5 fewer sacks. Not a huge difference, but if your team matures over the course of several years from starting freshman to starting seniors, that adds up to reducing sacks by about 1 per game.
One possible critique here is that “average” tackle experience is not the correct measure. Teams often put one of their better run blockers at right tackle and their best pass protector at left tackle. Thus instead of looking at the average, we should just look at the correlation between left tackle experience and sack percentage.
We don’t even need a graph here. We get almost the exact same trend as when the tackle experience data are averaged, and the slope of the trend line suggests that sack percentage slight increases as tackles get older. That is intuitively incorrect. A low r-squared value (<0.01) suggests left tackle experience doesn’t matter very much and a high p-value (0.31) implies statistical insignificance. This is admittedly somewhat baffling and definitely unexpected.
Question 3: Does the “weakest link” theorem hold for the passing game?
weakest link only in age, not awesomeness
When looking at the run game, the data suggested that the youngest member of the interior line was a better predictor of success than average experience of the interior line. In the passing game, the “weakest link” is a little less weak.
Unlike with the run game, average interior line experience appears to serve as a better predictor of sack percentage than does the “weakest link” along the interior of the line. The r-squared here is 0.02 and the p-value is 0.12, suggesting that the significance is marginal at best. It's not that the weakest link is a terrible predictor, just that the average experience of the entire interior line serves as a slightly better indicator of sack percentage.
At this point we can draw some basic conclusions from the first three questions. Total or average o-line experience only seems to be a marginal predictor of a team’s ability to keep their quarterback from getting sacked. Tackle experience, whether averaged or just taken as the left tackle, appears to have no relationship whatsoever with sack percentage. Just like with the run game, interior line experience seems to be the most salient characteristic with regard to o-line experience for predicting success in pass protection.
Question 4: What else could influence sack percentage?
One of the main critiques from the last study was that we’re living in a multivariate world and other potentially influential factors should be included in the analysis. I’m still working on getting myself up to speed regarding multivariate analysis, so I’m tentative to try and do too much with that now. We can, however, look to see how some other variables correlate with sack percentage.
Offensive Line Talent
4 star, 4 star, 5 star...sack?
Talent is one obvious potential factor in governing pass protection success. The chart below shows the correlation statistics for the star rankings of the o-line with regard to sack percentage. I’ve omitted the graphs here because none of these produce any correlation of statistical significance.
|Average O-Line Star Ranking||0.01||0.30||Low|
|Average Tackle Star Ranking||<0.01||0.52||Low|
|Average Interior Line Star Ranking||0.01||0.22||Low|
|Left Tackle Star Ranking||0.01||0.32||Low|
Surprisingly, star ranking of offensive linemen doesn’t seem to correlate very strongly with sack percentage. My guess is that this is due to star ranking of offensive linemen correlating closely with the difficulty of defense that a given team plays. For example, Alabama has talented linemen, but they play against tough defenses in the SEC. Toledo, on the other hand, has crappy linemen, but they play against week defenses in the MAC. Moreover, there tends to be very little variation in star rankings with non-BCS schools – almost everyone is a 2 star – so this may be obscuring some of the impact that talent (i.e., star rating) has on pass protection.
This can be accounted for, to some extent, by looking at only the BCS schools, where there will be more variation among offensive line star ratings and more consistency in the level of teams played. The chart below shows the correlation statistics for offensive line talent and pass protection success.
click to zoom with all BCS teams labeled
|Average O-Line Star Ranking||0.03||0.18||Low|
|Average Tackle Star Ranking||<0.01||0.64||Low|
|Average Interior Line Star Ranking||0.05||0.07||Marginal|
|Left Tackle Star Ranking||<0.01||0.87||Low|
Once again, it appears as though the interior of the line is the most crucial for preventing sacks. This corresponds well with the experience data presented in the first three questions. If we’re operating under the hypothesis that the interior of the line is more important than the tackles with regard to pass protection, which the experience data suggest, then we’d expect talent to matter more on the interior than it does at the tackles as well. It turns out that this is exactly the result we get. Whether looking at experience or talent, the interior seems to be the key to success.
I don’t know much about multivariate regression, but when you take both experience and talent of the interior of the offensive line into account for predicting sack percentage, an r-squared of 0.09 is produced. This is almost double the r-squareds produced by regressing experience and sack percentage and talent and sack percentage, and it suggests that these two factors work in tandem to determine the success of the offensive line regarding pass protection.
Unleashing the Dragon
A team’s tendency to throw deep, thus necessitating a longer drop and more time in the pocket, could be another influential factor governing sack percentage. I thought that yards per completion would be the best measure of a team’s tendency to throw deep, since yards per attempt could be equally as high for teams that throw quick, short passes, but complete a high percentage of them. Either way, we can look at both metrics.
click to see scatterplot of ypa and sack percentage
|Passing Depth Metric||R-Squared||P-Value||Significance?|
|Yards per completion||0.01||0.31||Low|
|Yards per attempt||0.01||0.20||Low|
These measures do not correlate particularly well with sack percentage. Yards per completion gives us the trend we’d expect – that sacks go up as yards per completion go up, but the explanatory value is weak as the p-value suggests insignificance. When doing a multivariate regression with yards per completion and interior line experience against sack percentage, the r-squared only rises to 0.056 from 0.05. It doesn’t add much explanatory value. Using YPA instead of yards per completion actually produces a trend where it appears that increased yards per attempt facilitate a decrease in sack percentage. That doesn’t make a lot of sense and the correlation and statistically insignificant anyway.
4 star talents, 5 star smiles
A third possible factor governing sack percentage is the skill of the quarterback. Perhaps sacks are less a matter of how good the line is and more a matter of how good the QB is. To measure this I look at each BCS quarterback’s star rating and their Rivals rating (4.9-6.1) to see whether their high school talent correlates with how often they end up sacked. You can’t really use any college stats as a measure of their talent, because those can be directly influenced by the play of the offensive line, and we’re trying to isolate QB talent as a separate and independent variable here.
click to zoom
There’s really not much here. Whether you go by star ranking (2-5 stars) or by the more precise Rivals rating (4.9 – 6.1), there’s no significant relationship between a quarterback’s talent and his ability to remain upright. R-squareds for both metrics are <0.01, and p-values are 0.75 – 0.80. On an individual level, the skill of a single quarterback might help him avoid sacks, but taken broadly across all BCS schools, quarterback talent doesn’t seem to be a factor.
all 10 linemen on FSU's 2-deep are upperclassmen /Miami Herald
Probably the most common critique in the previous diary was that depth should be taken into account. You can do this different ways: average or total experience on the 2-deep, the oldest player at each position on the 2-deep, or the percentage of upperclassmen on the 2-deep. For this study I'm using the last of these definitions, the percentage of upperclassmen. I'm defining "upperclass" as students who have been on campus for two years prior to this season. So redshirt sophomores and true juniors are both considered "upperclassmen," while true sophomores are not. The graphs below show the trends for both the line as a whole and the interior of the line.
click to see all teams labeled - Duke also has an all-upperclass 2-deep
The correlation is unexpectedly poor. The graphs above show line depth both across the entire o-line and just the interior of the line. In both cases, the trend line suggests that the more upperclassmen you have, the more sacks you give up. This doesn't pass the common sense test, and r-squareds for both are low (0.01) and p-values are high (>0.30) implying that the correlation is not statistically significant. It doesn't appear to be a matter of defining "upperclassmen" either. If you run the same regression using average depth on the line, you get the same spurious results. While line depth might be an excuse for any given team, across the entire FBS the experience of your starters seems to matter much more than the experience on the entire depth chart.
Modest but significant. Despite using a completely different metric for o-line success, sack percentage instead of YPC, the conclusions of this study are eerily similar to the previous one. Let’s begin with the (hopefully) obvious caveats. Offensive line experience explains a modest, though significant, amount of the variation in sack percentage across all FBS schools. We’re talking about 5% of the variation here, so there are clearly a lot of other factors that go into determining how good a team is at protecting their quarterback.
In a way, this study is much less about Michigan than it is about college football in general. The success or failure in pass protection for a single team can often be explained by factors that are specific to that team. For instance, Devin Gardner is essentially the Ben Roethlisberger of college football, refusing to throw the ball away or to be tackled until approximately half the other teams defenders are draped all over him. This certainly contributes to Michigan’s high percentage of sacks, but it is a difficult variable to account for and measure across all of college football.
That being said, offensive line experience does stand out as a particularly salient characteristic for explaining a team’s sack percentage. Although we’d assume that experience at the tackle positions would be more important in the passing game, the results of this study suggest that once again the interior of the line is what matters most. In contrast to the previous study, the “weakest link” (i.e., the youngest interior linemen) is not as good of a predictor as the average experience of the interior of the line.
Taking a comparative approach by looking at experience alongside other potentially influential factors provides some context for how important experience actually is. The chart below plots each of the metrics I’ve looked at in this study along with their r-squared and p-values.
|Independent Variable||Unit of Measurement||Data Set||R-Squared||P-Value||Significance?|
|Avg. O-Line Experience||Years||FBS||0.02||0.10||Marginal|
|Total O-Line Experience||Starts||FBS||0.01||0.28||Low|
|Avg. Tackle Experience||Years||FBS||0.01||0.67||Low|
|Avg. Interior Line Exp.||Years||FBS||0.05||0.02||High|
|Left Tackle Experience||Years||FBS||<0.01||0.31||Low|
|Average O-Line Talent||Rivals Stars||FBS||0.01||0.30||Low|
|Average Tackle Talent||Rivals Stars||FBS||<0.01||0.52||Low|
|Avg. Interior Line Talent||Rivals Stars||FBS||0.01||0.22||Low|
|Left Tackle Talent||Rivals Stars||FBS||0.01||0.32||Low|
|Average O-Line Talent||Rivals Stars||BCS||0.03||0.18||Low|
|Average Tackle Talent||Rivals Stars||BCS||<0.01||0.64||Low|
|Avg. Interior Line Talent||Rivals Stars||BCS||0.05||0.07||Marginal|
|Left Tackle Talent||Rivals Stars||BCS||<0.01||0.87||Low|
|Throwin' Deep A||Yards per Completion||FBS||0.01||0.31||Low|
|Throwin' Deep B||Yards per Attempt||FBS||0.01||0.20||Low|
|QB Talent A||Rivals Stars||BCS||<0.01||0.80||Low|
|QB Talent B||Rivals Rating||BCS||<0.01||0.78||Low|
|Total Line Depth||Upperclassmen %||FBS||0.01||0.33||Low|
|Interior Line Depth||Upperclassmen %||FBS||0.01||0.43||Low|
This provides some much needed perspective. IME this really highlights the importance of experience, and especially the importance of the interior line. Interior line experience correlates more strongly with sack percentage than does a team’s tendency to throw the ball deep (at least when measured by yards per completion), and it serves as a better predictor than average talent of an entire offensive line (at least when measured by star ranking). This is really interesting! If I was a betting wizard, and I am, I would have bet on average o-line talent being a much better predictor of success than experience. Also, although the experience of the starting interior linemen does correlate significantly with sack percentage, depth along the offensive line does not.
The factor that comes closest to interior line experience in terms of predicting sack percentage is the talent of the interior of the line. This should strengthen our confidence in the conclusion that the interior line is the more crucial than the tackles in keeping the quarterback clean. As previously touched upon, when we combine interior line experience and interior line talent as two predictors of sack percentage and run a multiple regression, the r-squared returned is approximately 0.09. This isn’t huge by any means, but it serves as a better measure of success in pass protection than any single metric we’ve looked at so far.
Why don’t the best linemen play on the interior? This was one of the main questions raised during the last study, and the assumption was that teams play their best lineman at tackle in order to protect their quarterback. This study suggests that the interior of the line is more influential in accomplishing that task. There are a couple potential explanations. QB injuries and fumbles could still be most common from blind side hits, and team’s put their best guy there in order to mitigate these disasters. I haven’t tested this but I imagine it’s something that could be done statistically. It could also be that the best linemen play at left tackle because that’s the most important line position in the NFL, where one might assume that tackles matter more (hence their bloated salaries). If you look at the relationship between left tackle talent in the NFL (as measured by salary) and sack percentage, however, you get a pretty spurious correlation.
The line does trend up a bit suggesting that higher paid left tackles allow fewer sacks, but the r-squared is only 0.01 and the p-value is 0.66. It appears that left tackles aren’t much better at predicting pass protection success in the NFL than they are in college. (This is obviously more complicated than I’ve presented here. For example, teams could spend more on left tackles to fix problems that are inherent in the rest of their line or in their offensive system, thus producing a trend where teams with higher paid left tackles actually have higher sack percentages. This study is about college though, so I’m just leaving this for now).
I guess I just don’t know, man. The argument about protecting the quarterback from taking blind side hits makes intuitive sense to me, but the data all suggest that the interior is a more important factor in pass protection. If anyone’s got any quantitative study on why it makes more sense to play your best lineman at left tackle, or that tackles are, in fact, more crucial to pass protection, I’d be interested to see it.
What does this mean for Michigan? Let’s reemphasize that the experience data explain a relatively small proportion of the variance in sack percentage and that for any single team, and for any given team, team-specific explanations probably outweigh the statistical ones suggested by youth or talent. That being said, Michigan is very young where it appears to matter most. They are, however, talented – at least according to their star rankings. If these players develop at an average rate, then our line should make some serious strides by the time it’s full of talented upperclassmen on the interior. This is somewhat disheartening for this year but should provide some hope for the future.
This hope, of course, is based on the expectation of reasonable player development. We don’t need the best coaches in the world, since they tend to recruit already talented and physically gifted players, but we do need to develop those players on par with the rest of college football. I have no idea whether Borges and Funk have histories of successful o-line development, but it might be something worth looking into. The potential is there, however, to have a very successful o-line with regard to both the running and passing game as these kids become upperclassmen.
This study isn’t meant to indict or absolve any of the coaches, and it really does say more about college football as a whole than Michigan in particular. I do, however, think it’s interesting to see how Michigan’s production compares to other schools given a specific level of experience. We’re pretty far below the trend line even when experience on the interior is accounted for, and especially when talent along the interior line is taken into consideration. I think that Devin Gardner’s inner Ben Roethlisbergerness has something to do with this, as does Al’s predilection for two man routes where both receivers go deep. Experience, especially on the interior, does seem to play a role though. I don’t think it’s really possible to accurately assign percentages of blame (it’s really just a guessing game), but until we get that sack percentage out of the FBS basement, rest assured, there will be plenty of blame to go around.
the past the future (let's hope)
Happy MGoThanksgiving to all!
the 36th image that comes up when you google "turkey football"
yes, I am taking this as a sign we beat Ohio
As many of us prepare for a long weekend with family and food and football, I feel that we should take a look at the space that we have here on the Internet to express our hopes and fears regarding Michigan athletics and, yes, give thanks.
We have this little corner of the Internet, provided most graciously by Brian, to discuss the trials, tribulations and triumphs of the athletic programs of our favorite school. Some of us attended Michigan (or are currently doing so), others did not or might be in the future, but we are united in our unwavering support of the University Of Michigan.
When it comes to football, we’ve watched the ups and downs of the program in the recent past and we still remain just as passionate and active in our concern and praise as we have ever been. In basketball, we’ve watched the watch of John Beilein take the program to heights that some of us had not seen in a long time. We follow all of our varsity sports, we get news on them all and we cheer when they do well. Some may follow only a few sports, but we are united in our wish that they do well.
We have this space to express our hopes and fears, our thoughtful analysis and sometimes our raw emotion. It can get a little tumultuous and dramatic at times around here, but we all express these things because of a desire for Michigan athletics to do well and to represent our school as we would like her represented. We should take a moment to step back from the now, look at this space, and be thankful that we have a place like this where we can share all these thoughts with fellow Michigan fanatics.
In a few short days, we will face Ohio State in one of the greatest rivalries ever conceived and the mood on the board has not been the best of late. We might be tested as a fanbase, but be thankful that there is a veritable army of thousands of active MGoBloggers (i.e., they have accounts at least, regardless of relative posting frequency) that will be watching with you and can be called upon to support you. Some of us will actually be there, some will be on the site or in the liveblog. We will be united by our desire for Michigan to win this game, however unlikely we may assume it is.
Speaking personally, I am thankful that this site is here and I am thankful that I have been entrusted to help support its mission. In my time as a poster and now moderator, I feel as if I have come to know many people here. Indeed, I have even met a few of you at various functions. It has been a net positive influence on my life and I have learned much here, and I am indeed thankful for that experience.
As a Michigan fan and proud alumnus, I am thankful for my experience with this fine institution and thankful for what it gave to me. I do my best to give back when I can because I feel a sense of community with University Of Michigan that I feel in few other situations. I feel a sense of community with this blog that I experience among few other groups of the collective fanbase. I am thankful to have the opportunity to interact with one of the most knowledgeable, sports-savvy fanbases on the planet and to count myself as part of such a group.
As I sit down with my family tomorrow, I will give a shoutout to my virtual one here. Hopefully, you will do the same.