For years, I used yards per play as my primary metric for college football. This metric captures the efficiency of how an offense moves the ball, and how a defense prevents this movement.
Then, Bill Connelly published an article that changed how I view football metrics.
To understand Connelly’s results, think about breaking down yards per play into two components. First, an offense needs to have some basic success on a play based on down and distance. For an offense, a play is a success if it gets the following fraction of the necessary yards for the next first down:
- 50% on 1st down
- 70% on 2nd down
- 100% on 3rd, 4th down
Success on a play brings a certain efficiency in terms of yards per play. However, an offense can help itself with explosiveness on successful plays. To make things easy, think of this explosiveness in terms of yards per play on successful plays.
Connelly showed that success rate is predictive. On offense and defense, success rate during an early part of the season has a strong correlation with success rate later in the season.
In contrast, Connelly found that explosiveness had zero correlation from early to late season. There is a huge random element in big plays. I’ve found the same in the NFL: yards per pass attempt on successful plays has little predictive power within the same season.
While I still track yards per play in college football, I rely on success rate (with opponent adjustments based on my PhD research) to evaluate offense and defense. Here are some surprising units after 7 weeks of the 2021 season.
Michigan State pass offense – The Spartans had over 12 yards per pass attempt against Rutgers. However, they benefitted from three touchdown receptions of over 60 yards to Jalen Nailor. The Spartans had a 40.7% pass success rate for the game compared to the 39.7% college football average.
Overall, Michigan State’s pass offense ranks 89th in my adjusted success rate, a significant departure from their 18th in adjusted yards per pass attempt.
Alabama defense – The Crimson Tide couldn’t hold Texas A&M’s back up QB from driving for a game winning field goal. And while they dominated Mississippi State on the scoreboard, they allowed a 40.5% success rate compared to the 40.8% college football average.
Doubting a Nick Saban defense might be dumber than deep frying a frozen turkey. However, Alabama’s defense ranks 29th in my adjusted success rate.
Ohio State defense – Through the first three games of the season, the Buckeye defense looked horrible. The seat under DC Terry Coombs grew warmer with every game.
However, Ohio State’s defense has surged the last three games, and they rank 24th in my adjusted success rate for the season. They are better against the rush (13th) than pass (59th).
Clemson offense – A perennial power like Clemson usually just reloads on offense. However, the Tigers offense ranks 71st in my adjusted success rate and even worse by yards per play (109th).
The obvious culprit is QB DJ Uiagalelei, tasked with the impossible chore of replacing Trevor Lawrence. However, Bob Stoll suggested on my podcast that the skill players might have a bigger role in this decline.
Western Kentucky offense – The Hilltoppers came into the season with many question marks, as they brought in transfer QB Bailey Zappe from FCS Houston Baptist. However, they have been essentially unstoppable and rank 1st in my adjusted success rate. They scored 31 points against Indiana and Michigan State.
Regression looms for this Conference USA offense. But with an awful defense ranked 125th in my adjusted success rate, Western Kentucky looks like an over team.
Football betting with a PhD edge
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