Trying to Normalize Best Defense in CFB History

ed.- bumped from the fanposts. good stuff.

First off, I'd like to say that what I love most about Roll Bama Roll is the amount of objective data and statistics that the site provides. The day RBR became my favorite website was the day I read my first Running Back Success Rates article. Something about the stats just speaks to Engineer in me. With that being said, this year with the Advanced Statistical Analysis (At least for the first half of the season), RBR became as awesome to me as must be to 13 year old boys.

In an effort to repay all the joy that RBR has given me, and inspired by the Defensive Efficieny posts from last week, I've attempted to take a similar look at the contenders that seem to be thrown around as the best in College Football History (well modern era anyway), to see if Dre was right, and 2011 Bama was the "greatest defense to ever take the field."

First off, I have selected 4 contenders based on the talking heads commentary in the aftermath of the BCSNCG.

1986 Oklahoma

1988 Auburn

2001 Miami

2011 Alabama

The goal is to try and normalize for the fact that in the last 20 years the popularity of 7 on 7 camps and the spread offense has driven up the productivity of offenses in CFB. My goal is to compare how many points a team averaged, versus how many points it scored on these great defenses. The more points a team is held below their average, the better the defense has performed. Also I have only included statistics for games against FCS (Div I) competition (Because it is hard to get data for non FBS teams) Check out the stats and comments after the break.

1986 Oklahoma:



On the season Oklahoma's opponents averaged 24.3 PPG when not playing Oklahoma, while those teams averaged 6.75 PPG against the Sooners. Overall Oklahoma held it's opponents to 17.5 points below their season average.

Additionally, Oklahoma tossed 5 shutouts, and 2 three point games. This is interesting to note, because while an offense can score to the thousands, a defense cannot do better than a shutout. The average PPG for those 7 teams was 22, which is almost 4 points better than OU season gap.

It is interesting to think that if those teams averaged 30 PPG, could oklahoma have held them to a 29 point gap, or even a 25 point gap? The 1986 Oklahoma Defense was indeed very very very good.

1988 Auburn:



On the season Auburn's opponents averaged 24.7 PPG when not playing Auburn, while those teams averaged 7.67 PPG against the Plainsmen. Overall Auburn held it's opponents to 17.0 points below their season average.

Additionally, Auburn tossed 3 shutouts, and 0 three point games. The average PPG for those 3 teams was 21.5, Which is 3.5 points better than Auburn's season gap. Auburn allowed teams to score 0.5 more PPG closer to average than Oklahoma.

Considering that Auburn's opponents only averaged 0.4 PPG more than Oklahoma's, and that the Tigers only had 3 games with less than 4 points, and Oklahoma had 7, I'm keeping the Sooner's in the top spot for now.

2001 Miami



On the season Miami's opponents averaged 26.6 PPG when not playing Miami, while those teams averaged 9.75 PPG against the The U. Overall Miami held it's opponents to 16.9 points below their season average.

Additionally, Miami tossed 3 shutouts, and 1 three point games. The average PPG for those 4 teams was 20.6, which is 3.7 points better than Miami's season gap.

At over half a point closer to average on the gap, despite teams only scoring 2 PPG more on the season, combined with the lack of shutouts, I think Oklahoma had a better defense than Miami. Despite the number of NFL stars to come off that Miami team, I guess something is to be said for coaching and team chemistry.

2011 Alabama



On the season Alabama's opponents averaged 27.9 PPG when not playing Alabama, while those teams averaged 7.1 PPG against the Tide. Overall Alabama held it's opponents to 20.8 points below their season average.

Additionally, Alabama tossed 3 shutouts, and 0 three point games. The average PPG for those 3 teams was 32, which is almost 12 points better than Alabama season gap.

While I am concerned about the lack of shutouts or 3 point games by the Tide, Alabama's opponents averaged almost 4 PPG better than Oklahoma's did, and Alabama still managed to hold them to a almost 4 PPG larger gap, which is almost an 8 PPG game swing. WOW!!!

Ed. As noted in comments, this is basically double counting.

At this point, I have decided that Alabama and Oklahoma boast the two best defenses in modes CFB history, and Alabama appears to have an outstanding claim over the Sooners. But as good as those numbers looked, I though they should look better, My memory is seared by 2 Non-Offensive TD's by Auburn, and a Pick-(almost)6 to the 1 in the Kent State game. I decided to try and adjust the number for Non-Offensive TD's, or TD's setup by a turnover inside the 15. Although I could find no official stats for these in 1986, I was able to find game recaps for the 86 Sooners, and tried to make due with that.

1986 Oklahoma Defense Adjusted for Special Teams and Turnover Scores:



Oklahoma's gap improved to 18.2 PPG (about 0.7 PPG increase), and the sub 4-points games remained the same.

2011 Alabama Defense Adjusted for Special Teams and Turnover Scores:



Alabama's gap improved to 22.8 PPG (2 PPG increase), and the sub 4-points games increased by 2 to five.

With the adjustments not only has Alabama increased it's gap by two, for almost a 10 PPG swing over Oklahoma, but and they have matched the Sooner's 5 shutouts.

I Know it is impossible to fully compare teams from different era's but I think the numbers above can make a compelling argument that Dre was not delusional, Alabama probably fielded the greatest D on turf!

Ed. For those commenting that GSU was not included, adding GSU in makes Alabama's overall PPG gap decrease from 20.8 to 20.4, which is still almost 3 PPG higher than Oklahoma. When looking at the adjusted stats for turnovers and special teams, it actually has no effect.

FanPosts are just that; posts created by the fans. They are in no way indicative of the opinions of SBN and the authors of Roll Bama Roll.

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