Perhaps the most important thing you can do in football is to maximize the return of your offensive possessions. You only get so many per game, and you don’t fully control how many you get. If your opponent is determined to sit on the ball for most of the contest, you simply won’t get as many chances to score as you otherwise would.
Some people may disagree with that though. They may argue that the most important thing you can do in football is to ensure your opponent gets the least out of their possessions as possible. A stifling defense can make up for offensive struggles and give the offense more possessions with which to work.
Regardless of which side you believe in, the same stat can be used to figure out how well your team is doing at both: points per drive. It’s not perfect since things like special teams and turnovers can affect that stat, but I think I can show that it’s pretty darn good at measuring how good a team is.
To calculate points per drive, you need two parts: points and the number of drives. Figuring out points is the easy part since you just look at field goals, rushing touchdowns, and passing touchdowns. That filters out special teams and defensive touchdowns.
I left out extra points and two point conversions because they have little to do with how offenses and defenses truly perform over the course of a game. I had no choice but to leave in lost/gained fumbles in special teams situations since there are no stat sources that separate them out. I’m mostly fine with that though since gaining or losing a fumble in special teams results in gaining or losing a possession. PATs on the other hand do not have anything to do with possession counts.
To calculate number of drives, I added up the following categories: punts, fumbles lost, interceptions, failed fourth down conversions, field goal attempts, and touchdowns of the rushing and passing variety. The NCAA official stats only have the offensive version of these stats and a few of the defensive, but the fantastic site cfbstats.com fills in the rest.
The top ten teams in offensive points per drive were the following:
- Texas Tech – 3.27 points per drive
- Oklahoma – 3.24
- Florida – 3.22
- Texas – 3.17
- Tulsa – 3.12
- Oklahoma State – 2.92
- Missouri – 2.89
- Penn State – 2.80
- Rice – 2.70
- Ball State – 2.698
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If you read any of my pieces on pace, this list will look familiar. All of these teams were either in the top ten of yards per play or points per play. The fact that they appear here should not be a surprise.
Here are the top ten teams in defensive points per drive:
- USC – 0.65 points per drive allowed
- Boise State – 0.75
- TCU – 0.79
- Iowa – 0.95
- Alabama – 0.98
- Ohio State – 0.99
- Florida – 1.00
- Boston College – 1.02
- Penn State – 1.09
- Utah – 1.13
Interestingly enough, Florida and Penn State are the only two teams in the top ten of both. If I said earlier that there were two teams were in both, I’d imagine many people would pick out UF, but probably not Penn State.
In any event, these two measures are not infallible predictors of great success. Houston (8-5) was 11th and Arizona (8-5) was 14th in offensive points per drive. Tennessee (5-7) was 11th and Clemson (7-6) was 13th in defensive points per drive.
In order to find out how good of predictors of success these measures are, I decided to run correlations for them with winning percentage.
I fully expected to see the negative correlation of defensive points per drive to be stronger than the positive correlation of offensive points per drive with win percentage. After all, how many times have we all heard that defense wins championships? Probably more than we can count.
Having been a believer in that myself, what I found shocked me.
The correlation of offensive points per drive and win percentage was 0.715. The correlation of defensive points per drive and win percentage was -0.711. In other words, there basically is no difference in their ability to predict success. Offense and defense are equally important.
Now, that is only one year’s worth of data at work. I can really only say that offense and defense were equally important in 2008. I am in the process of running data on past years to try to get a better idea of how they relate. For now though, they’re equal.
The next obvious step was to try to synthesize these two into one measure to see how high a correlation I could get. It is not as simple as adding the two numbers together because with one, a high number is good and with the other, having a low number is good.
I chose to go the route of deviation from the mean. So for offensive points per drive, I simply subtracted the mean from the team’s number. For defensive points per drive, I subtracted the team’s number from the mean. I then added those two together.
That process gave a single number to correlate with winning percentage. For now I’m calling it combined points per drive, but if you have a better name, leave it in the comments.
First, here are the top ten teams in combined points per drive:
- Florida – 2.12
- USC – 1.90
- Texas – 1.68
- Oklahoma – 1.65
- Boise State – 1.63
- Penn State – 1.61
- TCU – 1.46
- Tulsa – 1.25
- Texas Tech – 1.222
- Utah – 1.220
The worst record among them is Tulsa’s 11-3 mark. All eleven teams with a winning percentage above .800 are contained in the top 13 spots.
Given those observations, it should come as no surprise that the correlation between combined points per drive and win percentage is 0.923 for 2008. That is an extremely high correlation and about as high as you can expect for just two stats put together.
The important thing to remember is that this describes what teams did in the context of their opponents. This stat has not been adjusted for strength of schedule, so it would not make sense to take the above list and proclaim that Boise State is better than Penn State because of a 0.02 difference between them. A WAC schedule just doesn’t compare favorably to a Big Ten schedule, regardless of what you think of the current state of the Big Ten.
The top four beg some sort of interpretation though. It puts Florida and USC well ahead of the top two Big 12 teams, Texas and Oklahoma.
One way to interpret it is to say that Florida and USC were the two best teams and should have played for the national title. After all, there really isn’t that big a difference between the top five or six conferences.
Another way to interpret it is to point out that the Pac-10 and SEC were down, while the Big 12 had perhaps the best year of its entire existence. Of course Texas and Oklahoma would be lower; they played in the season’s toughest conference.
As I said I haven’t adjusted for schedule strength, so until and unless that happens, the debate will remain open. For what it’s worth, the NCAA says Oklahoma, Florida, and Texas (in that order) had the top three toughest schedules. USC’s slate clocked in at No. 38.
Regardless, the stat of combined points per drive seems to be a very accurate indicator of what degree of a winner a team was. I plan to explore this one further to see what else it might hold in store.