That’s the impression I get from this lengthy interview at Longhorn Digest.com (h/t Smart Football). In it, Diaz makes some excellent points about what you can take out of statistics, given certain limitations.
… many people judged defenses by the number of yards allowed, a stat called “total defense.” But the problem with total defense is that it doesn’t tell the total story, Diaz said.
“At N.C. State in ’04, we led the nation in total defense and we won five games. So there had to be something more to it than yards allowed, because yards allowed can be very deceiving,” Diaz said. “It’s really kind of flawed.”
Picture a team up by 20 points late in the game. That team is likely playing prevent defense, allowing the opponent to pick up easier yards by keeping the ball in front of the defense and limiting big plays. The other team racks up yards, hurting the winning team’s total defense. And the opposite is also true: if a defense is the side behind by 20 points, the opponent runs the ball into the line, making for easier stops, and therefore a better total defense, even if it doesn’t affect the game’s outcome.
Then, there are the issues with sample size and scheduling.
“The problem with college football is it’s actually the worst sport statistically because it’s such a small sample size and then [you have] the wide disparity of conference games versus non-conference games,” Diaz said. “The stats in terms of who finishes first in the country in total offense or total defense, a lot of that really has to do with scheduling.”
So what does he look at? Red zone touchdown efficiency, for one thing. (“You can win a national championship by making people kick field goals in the red zone,” Diaz said.) And for another, he pays attention to what some of those pajama-clad unshaven dudes are up to in their parents’ basements…
“I really think what’s happened, that is fantastic, is taking smart people plus computers plus too much free time,” Diaz said. “There are a lot of people doing outstanding work on the Internet.
“They’re taking the play-by-plays and adding more than just what the normal stats put out there,” Diaz said. “They’re not always on the right track, but sometimes they are. And that’s somewhat of a recent phenomenon.”
… specifically, “statistics like Slow Grind — the number of plays a defense forces an offense to take to score — and the FootballOutsiders.com S&P+ Ratings, a play-by-play success rate that factors for situation and competition.”
Grantham, by the way, comes off well and not so well when you look at some of these stats. Georgia was abysmal in red zone TD efficiency last season (88th nationally), so you hope that’s something he’s taking a close look at. Much better was Georgia’s 5th place ranking in S&P+, one slot behind Diaz’ Texas. Slow Grind is a stat John Pennington came up with; it’s simply a ratio of defensive plays to TDs. I ran last year’s numbers for the conference, subtracting out opponents’ TDs scored by punt and kickoff returns, and came up with these ratios:
- Alabama – 72
- LSU – 59.80
- MSU – 34.64
- USC – 32.12
- Vandy – 26.39
- UGA – 26.36
- UF – 25.70
- Arky – 25.33
- UK – 23.69
- UT – 23.50
- Auburn – 20.13
- Ole Miss – 16.45
Could be better, Georgia.