Math Wednesday: Measuring Efficient Defenses

By Chad Peltier on July 31, 2013 at 7:00p
10 Comments

Two weeks ago I took a look at three different efficiency metrics for offenses – yards per point, yards per play, and points per play – and studied how the Buckeyes did according to each statistic in 2012. 

Except to hear a lot of Tommy Schutt's name this year as wellCurtis Grant and the linebackers will need to step up in 2013

The Buckeyes were among the best in the country in terms of offensive yards per point and points per play, but in the mid-thirties for yards per play. 

While there is certainly a debate over which statistic is most important for capturing efficiency, I felt that it was necessary to view the three side by side in order to get the full picture of the 2012 offense. Primarily, Braxton and company were fairly efficient in their drives, but didn't always rack up tons of yards. 

Before diving in to the defensive statistics, here's a quick refresher on the three metrics. 

Yards per point is highly correlated with red zone efficiency – teams that score touchdowns instead of field goals – but is susceptible to turnovers and varies significantly throughout the course of the season. 

Yards per play is not affected by turnovers, but also doesn't capture points. It doesn't matter if the offense had a 99 yard drive if the drive ends with an interception at the one yard line. 

Finally, a team with a high points per play is able to minimize negative plays while still scoring touchdowns more often than field goals. It is closely related to yards per point.  

So how did the Buckeyes perform on defense in 2012? 

  Opp Yards per point Opp yards per play Opp Points per play
2012 Defense 15.8 (35th) 5.08 (28th) 0.312 (28th) 

While there was a fairly large difference between the three metrics for the offense, the defensive rankings are much more similar. 

The defense, as expected, was good but not great according to these three metrics. For instance, the Buckeyes' .312 opponent points per play is far off from the stellar 2009 defense, which averaged .19 opponent points per play. 

The Meyer-Hoke war will enter Year 2, but Gardner will face a much more efficient defenseShazier, Barnett, and Bryant will lead an efficient defense

There was far more stability across the three metrics for all teams, not just Ohio State. Alabama, Notre Dame, and Florida were among the top for each metric.

Furthermore, the defensive efficiency metrics appear to be highly correlated with overall success – much more so than for the offensive efficiency metrics. Alabama and Notre Dame are the top two overall teams according to both opponent yards per play and opponent points per play. 

The Buckeyes' defensive efficiency was steady under much of Tressel's tenure, then dropped suddenly with his departure in 2011. While coaching and scheme changes are partly to blame, it's hard for me to ignore the impact of losing great linebackers as well. Better linebacker (and Star) play will be crucial in 2013 for covering slot receivers, providing additional pressure on quarterbacks, and thwarting the run game. 

It is likely that the opponent yards per point ranking is lower than the other two metrics because the Buckeye defense created fewer turnovers than other elite defenses.

I've mentioned before that the Buckeyes should emphasize creating turnovers, but the problem is that turnovers are often completely random and unrelated to the quality of the defense as a whole. 

If the Buckeyes' lower yards per point ranking can mostly be explained by a low number of forced turnovers, then we are left with a fairly clear picture of the 2012 defense – good, but not great, and certainly not up to the later Tressel/Heacock standards. The good news with that is that the secondary will be full of veteran players, the linebacking core finally has some quality (if unproven) depth, and the defensive line is a row of four- and five-star recruits. 

Urban won't be satisfied with a mediocre defense in 2013, but will insist that the defense match the offense's efficiency. 

10 Comments

Comments

southernstatesbuckeye's picture

Great stuff!

And then along come the Bucks, "buckin" the trends through heart, grit and stubborn determination.

And you say we have the chance to be great?

Man, gimme me a Tony the Tiger!

Hovenaut's picture

I expect to see greater efficiency on both sides of the ball....year two in this program, more experience, talent, polish....adds up to offensive and defensive units better at what they do.

Buckeye Rocket Sci's picture

More awesome material, love it! 
Hopefully, and I expect, the defensive stats to get a large boost this year as we start filling some of those holes. After all, championships are won by defense!

"Nothing in the world can take the place of persistence" - Calvin Coolidge

urbanwarfare's picture

I think the silver bullets will take the "angry football" team to heart. I expect a lot of take always and sacks. Get here football season!

CentralFloridaBuckeye's picture

Great article Chad! 
Go Bucks!

MuraliPatel's picture

I keep looking for a 'lights out' type of defense, such as the ones we fielded in 2002 & 2005. In our two title game blowouts, I would argue that it wasn't our offense that let us down (to a certain extent, gameplanning did), but that our defenses being porous did, resulting in our teams being unable to generate significant pressure against Florida & LSU.
Here's to hoping this year's defense is up to par.

pjtobin's picture

Thank you Chad. This was another info packed great read. I think our defense will be much more like the 09 team this year. In order to win it all the d will have to play better. 

Bury me in my away jersey, with my buckeye blanket. A diehard who died young. Rip dad. 

vtbuckeye's picture

It seemed like last year was a tale of two defenses (pre-Boren at LB and post-Boren at LB).  What do the numbers show about the defensive improvement with that change (I wouldn't count the Indiana game because it was Boren's first game at LB and it takes time to get used to playing the new position)? 

Mirror Lake Jump's picture

The numbers never lie.

ejoceans's picture

Watching the 12-0 run last year again on BTN so far this week makes me a little cautious about our defense. I don't know if I'm alone on this one but man did our D stink at times!!! At the same time they were very good at times(more stinky than good tho).  I really hope we gel quicker this year and our suspect positions on D step it up big time to make this year something special.  Just the thought of some of those games last year makes me cringe. We were very fortunate in a lot of them to come out on top. The bad part is if our D wouldn't have gave up huge chunks at a time we would have won most of the games easily.  That being said we did win so its all good! haha  Honestly, no disrespect to Simon and Hankins but our D might be tougher this year and maybe faster too.  IDK only time will tell but high hopes for my boys. Go bucks baby!!!

Lets do this Brutus