Stat Session: Importance of Elite Defense vs. Offense, I

By Chad Peltier on May 7, 2012 at 4:00p
20 Comments
Simon eating breakfastI still can't believe we scored 73 points here

Urban Meyer's continual haul of elite defensive linemen and other defensive players in his two recruiting classes reinvigorates the seemingly eternal question of whether teams win national championships primarily because of their elite defenses or offenses. In this week's stat session I wanted to take a look at whether the old aphorism that "Offense sells tickets, but defense wins championships" is actually true. I think the majority of Ohio State fans would agree that, based upon our experience with the Tressel-led Silver Bullets of the 2000s, defense does in fact win championships. The common belief is that, save for the 2006 campaign with Ted Ginn and Troy Smith, Ohio State largely rode its defenses to victory year after year. 

Now, under the first year of Urban's Eternal Six-Year Reign, this question is all the more important. Urban has brought in an incredible defensive recruiting class while installing a new space-age offense. While it's obvious that teams need to be proficient at both offense and defense in order to win, is one more responsible for championships than the other? 

To measure offensive and defensive prowess, I use Football Outsiders' 2011 S&P+ Offensive and Defensive Rankings, which is comprised of three different measures:

1. Success rate, which measures whether any given play was successful. I.e. 50% of necessary yardage on first down, 70% on second down, and 100% on third/fourth. 

2. EqPts Per Play: A measure of explosiveness "derived from determining the point value of every yard line (based on the expected number of points an offense could expect to score from that yard line) and, therefore, every play of a given game."

3. Opponent Adjustments: A combination of the first two measures that is compared to expected output based upon their opponents and opponents' opponents. This rewards tougher schedules and punishes weaker ones. 

Any measure of offenses and defenses will be most valid when a game is still competitive, operationalized here as "a game within 24 points in the first quarter, with 21 points in the second quarter, and within 16 points in the second half." This controls for when teams ease off the gas pedal when victory was assured. It also ensures that Bielma's teams don't get extra points for pummeling Indiana in games that get out of hand. 

I then looked at how these measures of offensive and defensive strength were related to overall season success. I use two measures here: number of AP votes at the end of the year and total wins minus losses. I like the number of AP votes measure because it provides more information than a team's final ordinal ranking. For instance, Alabama wasn't better than LSU by the same amount that LSU was better than Oklahoma St. This measure should have perceptions about margin of victory and strength of schedule built in too. Finally, I controlled for strength of schedule directly. 

Here are my results:

Ap Votes Coefficient Std. Err T P>T 95% Confidence int
Off S&P+ 16.262 4.087 3.98 .001 7.76 - 24.76
Def S&P+ 4.8468 3.357 1.44 .164 -2.13 - 11.82
SoS 22.778 10.861 2.1 .048 .191 - 45.36
Wins - losses Coefficient Std. err t p>t 95% Confidence int
Off S&P+ .07848 .0242 3.24 .004 .028 - .128
Def S&P+ .04050 .0198 2.04 .055 -.000 - .081
SoS -.02384 .0643 -.37 .715 -.157 - .110  

A couple of things are readily apparent when comparing these two tables. First, an elite offense seemed to be more correlated with season success than defense during the 2011 season. Offensive S&P+ is statistically significant for both measures of season success, while defensive S&P+ ranking does not meet statistical signifcance at a 95% confidence level. Essentially, for each one unit increase in offensive S&P+, there is an average of 16 additional AP votes, compared to ~5 votes for a one unit increase in defensive S&P+ ranking. 

Picking apart defenses Can the 2012 Buckeyes ride their offense to success? 

There does seem to be some validity to the "offense sells tickets" part of the aphorism. AP voters appear to be impressed with offensive success more than defensive success. This is also reflected in the apparent need for some teams to run up the score for "style points" in the eyes of voters. 

I think another part of this is simply because of the relative power disparity between teams in the top-25 during the 2011 season. Alabama and LSU had ELITE defenses at the very top, but the other top teams won because of their offenses - look at Oregon, Arkansas, and Oklahoma State as key examples. All had adequate to good defenses, but were clearly built around their explosive offenses. A team's conference also plays some role here. Both LSU and Alabama are in the same conference division - because of the high defensive parity between the two, one team had to seperate itself offensively in order to even win the divison, then the MNC. 

Strength of schedule is statistically significant for AP voters, but not for our measure of wins minus losses. Clearly voters are more impressed by tough schedules and vote accordingly. It is also important to mention that strength of schedule is partly captured by the S&P+ ranking. 

In conclusion, both offense and defense are clearly important to winning games, but voters rate amazing offenses higher than amazing defenses. It's entirely possible that this is just a statistical artifact of a single year - we just looked at the 2011-12 season, which could have been an outlier. It's important to recognize that these results are preliminary and I'd be uncomfortable generalizing across all years. I will mention, however, that it is likely that a test of the 2010 season would offer similar results - Auburn certainly didn't win the championship based upon its stellar defense, but on the back of Cam Newton and Gus Malzahn's offense.

Tune in again next week when I'll be comparing Tressel and Meyer's recent offenses and defenses to see how each coach achieved consistent success. 

TL;DR It appears as though success was correlated with a strong offense more than a strong defense during the 2011 season. That is certainly not to say that defense is unimportant. Further, this may be unique to the 2011 season, but interesting nonetheless. 

20 Comments

Comments

cbusbuckeye's picture

I'm not sold. To me defense will always be more important. You can have an anemic offense that only manages 7-10 points a game but if your defense can stop anyone then you don't have to worry. Ideally you would have both great offense and defense, but of forced to choose I would opt for defense. 

nickma71's picture

That isn't saying anything. If the offense over powers the defense, was the defense not good, or was the offense just better?
The game is won and lost at the line of scrimmage. Which is a bigger failure of Tresselball than the often inept play calling. OSU will continue to always be relevant with Meyer because the defense isn't slowing down. And I agree that the defensive line looks as good as I can remember. I expect to see Noah Spence and Adolphus Washington regularly as an act of mercy by Meyer. Yeah, that is a joke. No mercy.

painterlad's picture

Ugh. Too much math.

To err is human. Really sucking requires having yellow stripes on your helmet.

SPreston2001's picture

Lol I said the same thing. Look at the way Bama shut down LSU with its defense in last years championship game. Defense def wins championships. But theres nothing like hanging 50pts on your opponent week in and week out lol. 

bassplayer7770's picture

Scores of 50-10 are more impressive than scores of 50-35.

Riggins's picture

I think ranking overall defense and overall offense are somewhat irrelevant when you're comparing conferences that don't play each other to a large degree. The B1G had a lot of highly ranked defenses last year if my memory serves. That's largely due to how inept some of the B1G offenses were in my opinion. The reverse is true when it comes to the Big 12. Lots of highly ranked offenses facing tissue paper defenses inflates their overall offensive statistics.

The statistics you compiled are interesting though, and I'm not trying to bash the article. It would be interesting to see how past years stack up.

Chad Peltier's picture

No worries and that's a fair point. The nice thing about the S&P+ ranking system is that it attempts to adjust for opponents - if the opponent's defense sucks, then you won't be rewarded as much for blowing them out. I also tried to further capture this by controllong for strength of schedule using an alternative measure. 

Riggins's picture

Yea, shame on me for not reading it accurately. If the S&P goes and does that, then it certainly gives a better representation than I originally thought. Again, nice article.

Chad Peltier's picture

Thanks - I appreciate it, Riggins. 

Bj Mullens over Sully's picture

Thanks to AP Stats class I understand the math behind this..... I personally feel defense is more important than offense, to note the difference in Ap voting for Offense v Defense, voters tend to like a team that wins say 45-38 over a team that wins 10-7, and are more likely to put them in the top 25 in my opinion.  So a great defensive team that lacks in offense would be ranked lower than a great offense team that lacks in defense.  However to win a championship, you need both a good offense and great defense or a great offense and good defense.

Favorite Buckeye: Obviously BJ Mullens

Run_Fido_Run's picture

I'm not sure about the outcome variables you use: AP votes (popularity contest) and wins-losses. The problem with the latter is that 8 of 12 (or 13)  games are in conference, which skews the overall (national) results.
Maybe I'd be tempted to look at how conference winners compare to their fellow conference members: How do they tend to rank in-conference in terms of defensive measurables versus offensive measures? Do conference winners tend to have the best defense in the conference, or the best offense?
Also, might look at bowl winners: take the 10 bowls (BCS bowls, Capital One, Outback, Cotton, Peach, etc.) and then run those numbers.

Bukirob's picture

IMHO using a single season to extrapolate something as fundemental as strong offense vs strong defense is a flawed exercise.
I do not believe you can have an offense that is inept... in other words if you take alabama's defense and put them on the 2011 OSU squad the buckeyes still lose several games.....
I believe a stellar defense allows a HC to take more risk in a big game with his offense or if he is winning a game by 10 or more it allows him to be more conservative with risk.  If you marry Jim Tressels view about where an offense can take risk based on feild position with his mindset about having a stellar defense with an offensive minded coach you have the best of both.... IMO that coach that closest resembles that is Urban Meyer....

You WIN with people.

 

 

WW Hayes

GABuckeye's picture

Look no further than the national championship game...  LSU = HORRIBLE offense, great defense... Alabama = GREAT defense, mediocre offense

Maestro's picture

Alabama averaged 430 yards and 35 points per game.  A little better than mediocre in my book.

vacuuming sucks

Maestro's picture

Cool stuff.  Love looking into the statistical world in football.  Thanks.

vacuuming sucks

William's picture

Thank you PoliSci 485 for helping me to understand this haha. Good article, definitely enjoy your pieces.

rdubs's picture

I'd be interested in seeing these coefficients plotted over time to see if there is any trends there.  For instance I could imagine that offenses got the upper hand briefly and then defenses evolved to stop things like the single wing or the triple option.  Currently we could be in a phase where the various forms of the spread have started to get the upper hand and defenses haven't made suffcient progress to stop them consistently.

razrback16's picture

I'm just glad the AP Voters don't get a say in the actual meaningful rankings. Too many of the AP Voters (Kirk Herbstreit comes to mind with his movement of Ohio State down to #9 from #5 after beating Arkansas in the SEC's backyard, as well as Doug Lesmerises), have no business rankings teams.

pcon258's picture

i read this during my stat class, so i feel like im not completely zoning out of class. difficult to understand, but i get the gist of it, and it seems to make sense. great, in depth article chad, i appreciate it. 

Doc's picture

I'm going to have to dust off my old statistics texts if you guys are going to start bringing math to the table.

"Say my name."