At Least Nick Sheridan Has People Skills

Submitted by colin on

One of the most lamentable aspects of being a college football fan as far as I'm concerned has long been the lack of quality stat keeping, as well as analysis. Matt Hinton (currently Dr. Saturday) and Chris at Smart Football are great, and if CFB Stats didn't exist, this post wouldn't exist, but it ain't no Fangraphs and those fellas ain't quite Tom Tango, who literally wrote The Book on baseball. Not that it's a fair comparison.

I bring Tango up because his stat wOBA inspired this post. wOBA (weighted On Base Average) is basically on base percentage gone plaid. Instead of dividing times on base (1B+2B+3B+HR+BB+HBP+ROE) by plate appearances, you decide how valuable in terms of runs each of those individual events are and then proceed (hence weighted). OBP is transformed into runs per plate appearance. Multiply times total PAs and you have the runs that batter was responsible for in that season. And scoring (or preventing) runs are the bottom line in baseball. In sum: bases get you runs get you wins. In football, it looks like this:

Yards - Turnovers = Points

This isn't exactly groundbreaking. It's a fundamental assumption behind Dr. Saturday's Life on the Margins, iirc, and I'm pretty sure this is what I'm going to find in Pete Palmer's Hidden Game of Football if and when it eventually ships to a2. And it's sorta-kinda what David Romer did, though not nearly exhaustive. The theory is good. The actual arithmetic is kind of annoying and is summarized in the following paragraph. Feel free to skip to the part where we find out just how crippling the impact of Nick Sheridan was and how much worse it could have been.

The key to being able to do this yourself is to figure out yards and turnovers in terms of points. I ripped the drive logs of every Big Ten conference game in 2008 from Yahoo. That'll give you yards/point, which came out to about 15. Then I plotted, in buckets of 10 yards, the percent of drives that resulted in a TD or FG based on the drive starting field position, except the last 30 yards which I averaged at the opponent's 15 due to relatively few samples.* This gives you average expected points based on field position. That plus average field position equals the average value of a possession, which is what you lose in a turnover. Not only that, but you give expected points to your opposition. According to my math, an INT was worth about -4 points. Thus points per throw is (Yds/15 + INTs*4)/attempts.

Feel free to comment

I Am Not An Expert. If my math is off, then suggest different constants/methods. They pass the sniff test to me; I ran assorted regressions on excel to test assumptions and it looked right. I'd be glad to share the drive chart database. Onward...

The Part Where We Find Out Just How Crippling The Impact Of Nick Sheridan Was

go here

It's sorted by pts/attempt, the relevant measure. Average was .33. Mr. Sheridan was dead last with those over 50 attempts with .15 points per attempt. An all around average team wins 4 games. The results indicate that an all around average team that replaced its average quarterback with Nick Sheridan would win 2 (converting to wins over average is easy enough). But it would also have tremendous team chemistry and at least one valedictorian. Wins aren't everything.

Also, check out Terrelle Pryor's numbers. Remember, this is just per throw. Rushing and sack yards are not included, nor is it defense adjusted. Having rewatched the Texas and Michigan games in HD (being able to see the d-backs helps), I was impressed. Tressel used the threat of Wells inside and Pryor's skills when bootlegged on the edge to great effect. The playbook seemed cut down, but his athleticism made it work. The sack numbers (scroll right in the g-doc) and somewhat inconsistent mechanics are the most glaring issues, but they were exaggerated by a bad pass blocking unit in front of him. In conclusion: barring injury, Pryor is going to be a terror. Surprise! Rivals #1 overall prospect in 2008 is projected to dominate. At least he'll probably be gone after his junior year.

*It's a shortcut and it probably understates how valuable possessions that start inside the 15 are. I actually think inside the 15 the function is probably no longer linear. I'm also sorry that this is isn't the most thorough or transparent presentation. It's a start though.

Comments

PeterKlima

February 13th, 2009 at 1:28 PM ^

It's not the lack of "perfection"... it is the "accuracy" that is at issue. The more uncontrolled variables, the worse the accuracy of the statistics.

It is interesting and somewhat reflective of reality, but it is not strong enough to rely on when making decisions.

Alton

February 13th, 2009 at 12:00 PM ^

I think these are good numbers; everything I have seen has a turnover, whether a fumble or interception, at pretty close to a 4-point swing.

I think the yards/point might be a little high. I have always used 12.5 yards/point instead of 15, and it works pretty well and has the bonus of being somewhat intuitive.

colin

February 13th, 2009 at 12:35 PM ^

I'm thinking maybe I should have seen the yards per point only on drives that ended in a non-turnover event. Otherwise, I may be double counting turnovers, which would leave the pts/yards high. It's in the same ballpark though, relative to how much a turnover costs.

Also, it's interesting to me that home field advantage is worth about a turnover. The home team starts with a turnover in its pocket, essentially.

AC1997

February 13th, 2009 at 12:48 PM ^

Very interesting post. As with any stats based analysis one of the primary purposes are to generate more thoughts and ideas. You see this in baseball right now with fielding statistics. Everyone has new ideas and they're all trying to quantify defensive performance.

The big thing that no one is talking about here is the field position result. Ignoring our horrible QB situation, look at the significant effect of a turnover on the probability of scoring. Specifically I'm looking at all of the fumbled kicks and punts. Those are basically gifts of points to the opponent. More than any one factor I think that will lead to a significant improvement in 2009 - we can't possibly botch that many KR or PR again. Those are automatic points.

I also agree with the other posters on the quality of the surrounding talent. In baseball it is hitter vs. pitcher. Therefore individual stats are easier. Chad Henne as a freshman was very good - but how good would he have been without Braylon Edwards? On stats alone Pryor looks very good. Maybe he is that good. Maybe the talent and style of play are able to limit his throws to only higher percentage opportunities - where he is throwing to NFL talent. Even more difficult is determining the quality of the defenders he's facing on each throw.

Personally, I think Pryor is a beast outside the pocket. But I was not impressed with him at all throwing the ball. If he gets better, he'll be a terror. If he stays the same? He'll be good as long as you don't ask him to throw 25+ times per game.

dex

February 13th, 2009 at 12:50 PM ^

Baseball is simply designed for statistical analysis - which is why it baffles me the old schoolers are so against the newer stats - and football is not as much.

But I think there's still a lot of room to improve football stats and make them much more useful than passing yards or completiton %.

The biggest difference to me is that baseball stats have evolved to be pretty frickin good at predicting future results, even on a team basis like PECOTA. Football still has a long way to go in that regard. But yeah, throwing out football stats because they aren't 100% perfect is silly, and numbers like this are a good help in figuring out who is more valuable or better than who beyond "that guy sucks" opinions based on first hand viewing.

This didn't add much, but I'm not a math type dude. I like to read it, though.

colin

February 13th, 2009 at 1:29 PM ^

performance = talent + luck, predicting wins and losses is always going to be a pain in football due to sample size. But nailing down the talent portion of that equation shouldn't be that rough. With enough work, I could have told you that State would be pretty average this year. I couldn't have told you they'd get as lucky as they did.

MI Expat NY

February 13th, 2009 at 1:33 PM ^

There are two aspects that make statistical analysis in baseball far more accurate than in football. The first, which has clearly already been mentioned is the individual nature of baseball vs. the team nature of football. The second is the greater volume of numbers to work with in baseball.

It has been noted that team stats in baseball can serve as a fairly good indicator of future success. Well in Baseball there's about 40 at bats per team per game. Extrapolated over 162 games. That's far more plays for analysis than 65 plays per game for 12 games in college football. When you add in the fact that fluke plays result in a significant amount of points, team stats become less predictive.

From an individual basis, football stats are even less helpful. While it's true that great players will have great stats, the inverse is not always true. And you certainly can't use individual stats as a basis for the claim of who is the better player. For instance, does anyone on this board really think Emmit Smith is the best NFL RB of all time? Great yes, but he owns the record because he ran behind a dominant Dallas O-line for years. Individual numbers are even more skewed in the College game, where strength of schedule, offensive schemes, collection of talent surrounding a player are all highly variable.

I think these stats provided by Colin are interesting, and certainly, to some degree, reflects what we saw this season. Clark was obviously the best QB in the Big 10 (by a wide margin) and Sheridan was obviously the worst. Using these stats to rank 2 through 13 might be a bit much, though.

Yinka Double Dare

February 13th, 2009 at 1:38 PM ^

Football statistical analysis has actually yielded some really interesting stuff. For example, turnovers, and in particular, fumbles. CAUSING fumbles (or preventing them on offense) is a repeatable skill of a team. However, RECOVERING fumbles is not. Fumble recovery is effectively random, and across all games would approach 50% recovery by the offense and 50% by the defense. There's no correlation from year to year on fumble recovery percentage of a team.

The Football Outsiders DVOA stats by down also can yield some interesting stuff. Teams that are way better on 3rd down compared to their other downs tend regress as a team the next year, and vice versa. Teams are not repeatably better (or worse) on third downs compared to their other downs under FO's stats.

That kind of info I think is valuable. It's like the realization that pitchers (other than knuckleballers) have zero control over what happens to the ball after it's hit in play, and that on average they will tend to have a batting average on balls in play of around .295, .300 (with a "normal" band around it), so you can see when a pitcher is doing it with skill (if their BABIP is around the average or higher) or luck (when their BABIP is well below the norm). Also useful for finding bounceback or regression candidates for the next season so you don't overdraft some guy in your fantasy draft.

colin

February 14th, 2009 at 7:35 PM ^

because you're glad you can't understand statistics or declaring that you don't need statistics to understand the game, because you get everything you need from watching. either way, you're thumbing your nose at the post, which attempts to translate performance into points. game points. not hit points. or ball points. the ones that go on the scoreboard.

Sgt. Wolverine

February 14th, 2009 at 10:53 PM ^

No. I'm saying I don't need to "understand" the game as you're defining it to enjoy it as a fan. I don't need to translate anything into anything to know that one team won and the other team lost. This information can be important to people like coaches, but a lot of fans don't need to analyze the game to enjoy it.

So I'm not so much thumbing my nose at the post as I'm saying that I don't think I'd enjoy watching the game very much if I tried to analyze it like this. I don't know if you think this way, but I see too many stat-happy fans who look at fans who don't share their penchant for in-depth analysis as lesser or ignorant, and it gets a little old.

Seth

February 14th, 2009 at 7:18 AM ^

I, for one, love statistical analysis. Highest order! Bravo!

The only downside I think is every time I read something like this that takes an honest mathematical approach to college football, it makes my brain bleed that much more when Herbstreit et al. blather during the game about how Tim Brewster practices fumble drills.

There was a time when I thought you had to be a football genius in order to draw on a teleprompter. Thanks to this blog, and other informed individuals, I've taken to leaving dishes out and the toilet seat up on football Saturdays so Misopogal's nagging can drown out the stupid.