Thursday, June 4, 2009

Georgia Tech's Rush Defense Efficiencies

Tomahawk Nation and Gobbler Country got me interested in looking at the efficiency stats of our offense and defense. However, there is a slight flaw with what GC and TN do in their analysis. They don't list their assumptions or acknowledge any possible errors in your statistics. As any engineer should know, when doing a data analysis, you need to list your assumptions rather than just getting lost in the numbers and accepting them for fact. So here we go:

Assumptions and Possible red flags:
1. Injuries are unaccounted for in these statistics. Efficiency stats reflects a world where the same players were playing the same position for every game.

2. Statistics have a limited argument in football.

3. Teams prepare in separate manners. Boston College had a lot less time and information to work with than UNC did. You also can't add in Clemson's debacle right before our game. Those could all be potential factors in affecting the efficiency numbers below.

4. Data is from In-Conference statistics only. Out of Conference are considered outliers and have been thrown out.

With all that being said, let's have some fun and see what we got and see how GT did last year against expectations.

Note 1: Sacks have been taken out of the equation. Sacks are a factor that plays into a rushing statistic but does not show how we stop the run itself.

Note 2: The small the number, the better the number for GT.

Abbreviations: YPC - yards per carry; Rush Plays - opponent carries minus sacks; ExpYds - expected yards for the opponent; Actual Yards - opponent yards with sacks taken out; Efficiency - GT efficiency.

Georgia Tech Rushing Defense Efficiencies-2008
Opponent YPC Rush Plays Exp. Yds Actual Yds GT Sacks Sack Yards
Boston College 3.9 41 147.0 120 3 15 0.918
Virginia Tech 4.3 46 193.6 199 1 6 1.059
Duke 3.5 20 63.1 35 2 14 0.776
Clemson 3.8 24 87.5 51 1 12 0.720
Virginia 4.0 36 141.7 126 1 14 0.988
Florida St. 5.0 36 155.0 196 5 38 1.510
North Carolina 4.0 42 158.8 186 2 23 1.316
Miami 4.7 25 109.2 105 2 11 1.063
Season 4.2 270 1055.0 1018 17 133 1.091

Remember this is with sacks taken out. When sacks are added to the equation and a more true traditional rushing defensive number is looked at, the Yellow Jacket Rushing Defensive Efficiency drops to 1.078. Not a dramatic drop which tells me that our defense did not rely on sacks heavily to stop opponents. This could be an indication that the loss of a significant portion of our defensive line is NOT as serious as some might think.