so much for that
Red zone defense
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I was reflecting on our win yesterday, and how crucial it was that our defense held IU to field goals on several drives that went deep into our territory. I got to thinking about red zone percentage numbers - the way everyone calculates them, a field goal is worth the same as a touchdown. Doesn't make much sense, does it? If the other team's going to score, you'd much rather have a team that allows three points per trip inside the 20 than one that allows six. So, I went to the NCAA website and grabbed the redzone defense numbers, and calculated a sort of weighted percentage. Basically it's this:
weighted percentage = (red zone TDs + 0.5 * red zone FGs) / total red zone trips
Yes, I know that a TD usually winds up being worth 7 points, but a 2:1 value for TDs vs. FGs seemed like a good starting point. Why did I bother doing this? Well, mostly just to see if numbers justified my perception that regardless of how the defense as a whole plays, it's really tightened up inside the 20s. How do we measure up? Well, I put the whole Big 10 on a...
Chart:
EDIT - I added in the "PPT" column. This is the "points per red zone trip" metric discussed in the comments, and it's what I used for my red zone offense post here. This didn't change the rankings too much - if I reranked based on the new metric, Wisconsin would leapfrog Northwestern and Illinois by a slim margin, but that's it. Also of interest is that using the PPT metric, OSU gets jumped by Arizona and Louisiana-Monroe, leaving the Bucks dead last in NCAA D1A. That makes me smile inside, even if it is just an artifact of a small sample size.
weighted percentage = (red zone TDs + 0.5 * red zone FGs) / total red zone trips
Yes, I know that a TD usually winds up being worth 7 points, but a 2:1 value for TDs vs. FGs seemed like a good starting point. Why did I bother doing this? Well, mostly just to see if numbers justified my perception that regardless of how the defense as a whole plays, it's really tightened up inside the 20s. How do we measure up? Well, I put the whole Big 10 on a...
Chart:
| School | Drives | Red zone % | Rank | Weighted red zone % | Weighted rank | PPT |
|---|---|---|---|---|---|---|
| Penn State | 8 | 63% | 7 | 44% | 3 | 2.88 |
| Indiana | 10 | 70% | 20 | 55% | 17 | 3.80 |
| Michigan | 15 | 73% | 27 | 57% | 21 | 3.87 |
| Iowa | 7 | 100% | 111(t) | 64% | 42 | 4.14 |
| Minnesota | 12 | 83% | 63 | 67% | 51 | 4.50 |
| Purdue | 16 | 81% | 58 | 75% | 89 | 5.19 |
| Illinois | 10 | 90% | 93 | 80% | 106 | 5.50 |
| Northwestern | 15 | 87% | 79 | 80 % | 108 | 5.53 |
| Wisconsin | 13 | 92 % | 102 | 81 % | 110 | 5.46 |
| Michigan State | 12 | 100 % | 111(t) | 88 % | 113 | 5.92 |
| Ohio State | 5 | 100 % | 111(t) | 90 % | 118 | 6.40 |
Note - "Red zone %" and "Rank" are the defensive numbers straight from the NCAA website, and the weighted numbers are mine.
So what does this mean?
It's still early in the season, but we can start to see a few things.
- First, I was right - Michigan is near the top of the conference, and has done a pretty good job of keeping folks out of the endzone when they get inside the 20.
- Holy hell, MSU. If we get in the red zone, we should get points - probably 6 of them.
- Iowa's interesting - every red zone trip, they've given up a score. However, they've done a damn god job of limiting people to field goals. (Admittedly, that's on only 7 drives.)
- Penn State's been pretty darn good, allowing a TD on only 25% of their red zone trips.
- Before you start gloating about OSU being at the bottom of the list, look at the number of drives. That's right, they're allowing an average of 1.25 red zone drives per game. Of course, they gave up touchdowns on almost every trip, but small sample size blah blah.
- Virginia Tech checks in at #4 nationally, allowing TDs on only 4 of their 17 defensive red zone trips. They must put something in the water in Blacksburg, cause that's ridiculous.
- Oklahoma and Florida are #2 and 5, respectively. It's just not fair to put defenses that tough opposite offenses with the kind of firepower they have (assuming their QBs are healthy, anyway.)
EDIT - I added in the "PPT" column. This is the "points per red zone trip" metric discussed in the comments, and it's what I used for my red zone offense post here. This didn't change the rankings too much - if I reranked based on the new metric, Wisconsin would leapfrog Northwestern and Illinois by a slim margin, but that's it. Also of interest is that using the PPT metric, OSU gets jumped by Arizona and Louisiana-Monroe, leaving the Bucks dead last in NCAA D1A. That makes me smile inside, even if it is just an artifact of a small sample size.
September 28th, 2009 at 12:47 AM | 
Alright, now it's done...
Alright, now it's done...
September 28th, 2009 at 12:15 AM |
uh oh...a teaser lol.... not
uh oh...a teaser lol.... not
uh oh...a teaser lol.... not having seen the data, the red zone defensive stats are probably better than the normal defensive stats for some odd reason.
Strictly business...Not personal.
September 28th, 2009 at 10:24 AM |
Maybe . . .
Maybe . . .
GERG is great at scheming the red zone, perhaps?
September 28th, 2009 at 12:43 AM |
why not 7:3 td:fg ratio?
why not 7:3 td:fg ratio?
why not 7:3 td:fg ratio?
September 28th, 2009 at 12:50 AM |
Partially because a TD
Partially because a TD
Partially because a TD doesn't always result in 7 points - sometimes you miss the PAT, sometimes you go for two. Mostly it's because I like round numbers, and using a 50% weighting is a pretty good approximation. If I do this again in a few weeks, I'll take a little more time and see if using a 7:3 ratio makes much of a difference.
September 28th, 2009 at 1:01 AM |
Interesting numbers. You
Interesting numbers. You
Interesting numbers. You make the good point about OSU only having 5 drives going in to the red zone. They have only played one decent opponent, however that is impressive.
I am not sure, if Michigan's D tightens-up in the 20...but perhaps it has to do with having the type of athletes that play better in a tight space, rather than wide open...aka better at making quick athletic plays rather than having to think and adapt to wide spread fields....(youth and inexperience playing a larger factor in wide fields rather than tight quarters)
that may go for the coaching decisions as well....
also...too many drives ending up down there...it would be nice to see that overall number reduced.
Strictly business...Not personal.
September 28th, 2009 at 4:33 AM |
Interesting to note
Interesting to note
That the top 3 in the Big Ten stay in the same order regardless of how it is calculated. Also, any thoughts on the value of a missed field goal rather than getting a turnover? M has been the beneficiary of I think 2 missed field goals inside the red zone, and this seems more on the other team than our D. Any way to adjust these numbers to account for this?
Wiggum: Do they have Krusty partially gelatinated non-dairy gum-based beverages?
Lou: Mm-hm. They call 'em, "shakes."
Eddie: Huh, shakes. You don't know what you're gettin'.
September 28th, 2009 at 7:26 AM |
Interesting concept, but
Interesting concept, but
Interesting concept, but there's no way to do that without getting a lot more data. All that's on the NCAA website is the number of red zone drives, TDs, and FGs - although it does break down TDs into rushing vs. passing, which I might look at later.
September 28th, 2009 at 4:37 AM |
Nice work
Nice work
I look forward to see how these numbers move through the balance of the year into conference play.
I am also now curious on what the numbers look like on the other side of the ball.
Everyone has a plan...until they get punched in the mouth.
September 28th, 2009 at 6:39 AM |
Definitely a much better
Definitely a much better
Definitely a much better metric than the regular red zone efficiency. Nicely done.
Now how about one for the offense?
September 28th, 2009 at 7:22 AM |
Could be done without too
Could be done without too
Could be done without too much difficulty - I'll try to look at it tonight.
September 28th, 2009 at 10:23 AM |
Good job with this +1
Good job with this +1
I have always thought the standard red zone efficiency numbers which were blind to FG vs. TD was total bogus. Just a thought though: maybe we could add a metric of "average points scored per red zone attempt"?
September 28th, 2009 at 2:00 PM |
That's a good idea...
That's a good idea...
Points per red zone attempt is much more intuitive than a nebulous percentage or efficiency... the question is scoring. The data I have doesn't tell me whether each touchdown was followed by a PAT, a 2-point conversion, or whatever. Should I just round and assume everything is worth 7 points? Not sure what the best method is. I could put something together, though.
EDIT - I just noticed that they actually have total red zone points in with the rest of the data... I can use that to calculate points per red zone trip. I think I'll do that when I look at the offense later, since that's essentially the type of metric I'm going for here.
September 28th, 2009 at 11:00 AM |
Drive efficiency
Drive efficiency
So in looking at this metric, and specifically the OSU point that is made, now there *IS* a reason to be looking at time of posession. Why? It has to do with the number of total posessions.
A team with a high TOP may also be a team that has long drives. If long drives reduce the number of posessions the opponent has, then the OSU effect isn't as impressive.
In other words, if OSU faced 20 opponent drives this season and let 5 into the redzone, that is way less impressive than if they faced 40 drives and let only 5 into the red zone.
Similarly, our allowing 16 redzone trips isn't as bad if we've faced twice as many opponent drives as OSU (which I suspect ISN'T the case, btw...).
I would suggest adding a "total # of drives faced" column and/or a "percentage of drives that end up as red zone drives" column.
Good post... +1.
September 28th, 2009 at 11:40 AM |
I am confused by any defensive chart...
I am confused by any defensive chart...
that puts Ohio State and Penn State on opposite ends.
September 28th, 2009 at 12:24 PM |
Nice work
Nice work
+1 for Statistical Masturbation tag
September 28th, 2009 at 1:22 PM |
(FG attempts + TOD) / total red zone attempts
(FG attempts + TOD) / total red zone attempts
I'd argue that
(FG attempts + TOD) / total red zone attempts
would be an even better metric, based on these assumptions:
1. A college kicker should make any field goal from less than 38 yards. Missed field goals are entirely the kicker's fault. Therefore, any field goal attempt should be seen as a red zone success.
2. Blocked field goals are credited to special teams and not the defense.
3. TOD (turnovers on downs) are considered successes, but no better than FGA, since the offense could have kicked a field goal.
4. Defenses should still be penalized for giving up touchdowns on fourth down.
5. Turnover margin is nearly random.
I don't have time to calculate this for B10 teams now; maybe I'll do it later.
Also, hey, JLo. Nice picture.
September 28th, 2009 at 2:22 PM |
Simplify
Simplify
What up, Jeag?
The issue with more complicated metrics is that not all of this stuff is readily available (at least, not on the NCAA site). For the red zone stats they keep, a missed field goal equals a blocked field goal equals a turnover equals a failed fourth down conversion.
Now, you could approximate the sort of stat you're talking about, by taking
(red zone trips - # of TDs) / red zone trips
This would account for field goal attempts and TOD, and if turnovers are truly random then over the course of a season all of the teams percentages would be affected equally. Of course, the distribution isn't really random, so certain teams would get rewarded based on luck, but it would be tough to fix that without getting more data from somewhere else.
I think I'm going to lean towards the points per red zone trip metric that someone suggested earlier, as that's pretty damn easy to calculate, and it reflects the main goal of the defense: keep points off the board.
For anyone who wants to take a look at the numbers, I'm getting them here:
http://web1.ncaa.org/mfb/natlRank.jsp
Sorry for hitting save before I had the numbers in - didn't mean to leave you all hanging.