LANDOVER MD - SEPTEMBER 06: Quarterback #5 Tyrod Taylor of the Virginia Tech Hokies is tackled by defensive end #40 Tyrone Crawford linebacker #33 Tommy Smith and linebacker Aaron Tevis of the Boise State Broncos at FedExField on September 6 2010 in Landover Maryland. (Photo by Geoff Burke/Getty Images)
[W]hat Im semi curious of is does it take into account what down the play was on. Because given a scenario like FSU vs UF 2003, PK Sam’s bomb of a catch was great and was what scored the winning touchdown, but the 4th down conversion the play before made those points possible. So essentially what I mean is that the 24 yards Dominic Robinson got should count just as much as the 52 yard bomb that PK Sam caught. I understand it wasn’t as explosive, but without the conversion on 4th, the 52 yards bomb never happens.
So what I’m really wondering is how would you be able to combine the success rate into the epp and generate an importance per play of a drive.
This was something I covered in Varsity Numbers a couple of years ago.
The concept behind EqPts is a simple one. Each yard line has a point value assigned to it based on the number of points an offense can expect to score in a possession involving a play from that yard line. The 20-yard line is worth 1.179 EqPts. The opposing 20-yard line is worth 3.898. Each play is assigned a point value based on where the play started and where it finished. The slope is different throughout the field. A gain of five yards from your 20 to your 25 is worth 0.064 EqPts. From the opponent's 40 to the opponent's 35: 0.441 EqPts. From the opponent's 10 to the opponent's 5: 0.582 EqPts. The concept of EqPts is intended to give more weight to more important gains.
Second- and third-level EqPts are in essence derivatives of the EqPts concept. Second-level EqPts take two factors into account: yard line and down. First down from your 20 (1.488) has a different point value than third down from your 20 (0.808). Another example: First down from the opponent's 10 is worth 4.881 EqPts, second down is worth 4.477, and third down is worth 3.818. It's not a hard concept to explain; the points you can expect to score go down as the down markers go up.
With second-level EqPts, a play can have a negative value without losing yards. As mentioned in the quote above, second-level EqPts don't tie as closely to actual point values (because of the possibility of negative values, the sum of all second-level EqPt values is only about 82 percent of the sum of first-level EqPts), but looking at second-level Points Per Play (or 2ndPPP) adds a factor of timely play-making to the equation -- because in football, as in comedy and sniper-fire, it's all about timing -- while further subtracting empty gains on second- or third-and-long.
The 2ndPPP concept is not one that I've pursued in great detail, and for two main reasons: 1) I need more hours in the day, and 2) its correlation to overall quality is lower than that of PPP. For a while, I was combining PPP and 2ndPPP for the 'P' portion of S&P+, but the correlations just did not support it. I think there is value in 2ndPPP (and 3rdPPP, which takes into account down and distance), but it is as much contextual as evaluative. For every interesting observation you can make (the ten highest 2ndPPP averages from 2005-10 all happened in 2008), you can make a nonsensical one (the top 2010 offense according to 2ndPPP: New Mexico). Put this on the long-term, "need to look into this" list.
Now, to Defensive PPP. We start with the same anchors as always.
Worst Single-Season Defensive PPP, 2005-10
1. North Texas (2008): 0.61
2. UNLV (2010): 0.54
3. New Mexico State (2010): 0.51
4. Eastern Michigan (2010): 0.51
5. Eastern Michigan (2008): 0.50
6. Utah State (2006): 0.49
7. Temple (2006): 0.49
8. Washington State (2009): 0.49
9. Rice (2005): 0.48
10. Rice (2007): 0.47
Other Teams of Note
13. Washington State (2008): 0.47
17. Washington (2008): 0.47
21. Iowa State (2008): 0.46
22. Minnesota (2010): 0.46
32. Washington State (2010): 0.45
Again, there is no faking PPP. There are many different ways to become efficient -- Wake Forest's Jim Grobe mastered the art of misdirection for the Demon Deacons for a few seasons -- but there is only one way to be explosive over the course of a full season; 1a) be fast, 1b) get into the open field a lot. Defensively, then, there is only one way to allow a ridiculously high PPP: 1a) don't be fast, 1b) allow teams into the open field a lot. Therefore, there are few surprises on this list. The teams with the worst overall Def. PPP are the slow mid-major defenses who give up a ton of big plays. The BCS teams on the extended list are the same.
(And once again, 2009 Washington State makes an appearance. Right after I write my "How 2ndPPP Proves that 2008 Was the Greatest Offensive Season of All-Time" book, I'll write my "What Special Confluence of Events Caused a Major Conference Team to Be as Bad as 2009 Wazzu" book.)
Best Single-Season Defensive PPP, 2005-10
1. Virginia Tech (2006): 0.17
2. Nebraska (2009): 0.18
3. Miami (2005): 0.19
4. Florida (2009): 0.19
5. USC (2008): 0.19
6. TCU (2009): 0.19
7. TCU (2006): 0.19
8. Alabama (2009): 0.19
9. Iowa (2009): 0.19
10. Ohio State (2009): 0.19
Other Teams of Note
11. Penn State (2009): 0.19
12. Penn State (2005): 0.20
13. West Virginia (2010): 0.20
14. Boston College (2005): 0.20
15. Ohio State (2006): 0.20
Lots of 2009 on that list. If 2008 was A New Offensive Hope episode of the Spread Wars trilogy, 2009 was The Defense Strikes Back. (The Jar Jar Binks in this weak Star Wars analogy? Barry Switzer. I don't have to explain myself.)
While TCU makes appearances on both the PPP and Success Rates lists, as a whole, comparing teams' success rates to PPP give you an interesting clue into their identity. Teams like Boston College, Iowa and Penn State try to prevent big plays and force you to run as many plays as possible to score (wagering that you cannot, in fact, do that). Meanwhile some other teams -- in 2010, good examples appear to be Oklahoma, Texas and Miami -- attack a bit more and try to keep success rates low while risking a big play or two.
So here is your list of 2010 defenses, ranked in order of opponent-adjusted PPP+ (which, as always, we will explore in the future):
|2010 FBS Defenses, Ranked by PPP+
|Rk||Offense||ClosePPP+||Raw PPP||Rk||Rushing PPP||Rk||Passing PPP||Rk|
|63||San Diego State||98.0||0.30||39||0.25||26||0.36||57|
|83||San Jose State||88.6||0.40||105||0.39||110||0.40||85|
|119||New Mexico State||66.5||0.51||119||0.49||120||0.53||114|
Though they did something other Boise State teams haven't done -- lose a game -- advanced stats suggest that the 2010 Broncos were Chris Petersen's best team yet. Thanks to the presence of two undefeated BCS conference teams, BSU almost certainly wouldn't have made the national title game even if they hadn't lost to Nevada via two baffling missed kicks (a shame, as I'm pretty sure they were as good, or very nearly as good, as the two title game participants), but they were potentially the best all-around non-BCS conference team of the "We have play-by-play data for it" era.
(I still need a better name for that.)
By the way ... in said play-by-play era, West Virginia's defense has been fantastic, horrific and fantastic again. A tough feat.