I always enjoy Matt Melton’s postmortem take on conference yards per play numbers. He’s just posted his take on the SEC here. The picture may surprise you a little.
… here are the Yards Per Play (YPP), Yards Per Play Allowed (YPA) and Net Yards Per Play (Net) numbers for each SEC team. This includes conference play only, with the championship game not included. The teams are sorted by division by Net YPP with conference rank in parentheses.
Yep, that’s Georgia boasting the best net number in the division and third best in the conference. Obviously nobody’s going to describe Georgia’s season in that way, so how to explain? Well, first start with Matt’s general caveat.
College football teams play either eight or nine conference games. Consequently, their record in such a small sample may not be indicative of their quality of play. A few fortuitous bounces here or there can be the difference between another ho-hum campaign or a special season. Randomness and other factors outside of our perception play a role in determining the standings.
There are a few factors inside of our perception that can play a role, too. Here are four:
- Georgia was twelfth in the SEC last year in offensive plays run in conference games. With a couple of exceptions, that was a pretty steady reflection of Richt’s approach on offense over the years.
- Georgia was +1 in turnover margin in its eight 2015 conference games. (It was +14 in 2014.) That was good for fourth. Unfortunately, Florida was first last season, at +8.
- Georgia finished thirteenth in third-down conversion rate last season. Missouri was the only team worse.
- In 2014, Georgia was the top team in the country in Football Outsider’s field position rankings. Last season, the Dawgs wound up 63rd on the list. That was only good for eighth best in the SEC. Florida and Tennessee finished in the top five.
All of that was a drag on a team that at least statistically generated respectable ypp numbers.
… As it is, we have to make do with the handful of games teams do play. In those games, we can learn a lot from a team’s Yards per Play (YPP). Since 2005, I have collected YPP data for every conference. I use conference games only because teams play such divergent non-conference schedules and the teams within a conference tend to be of similar quality. By running a regression analysis between a team’s Net YPP (the difference between their Yards per Play and Yards per Play Allowed) and their conference winning percentage, we can see if Net YPP is a decent predictor of a team’s record. Spoiler alert. It is. For the statistically inclined, the correlation coefficient between a team’s Net YPP in conference play and their conference record is around .66. Since Net YPP is a solid predictor of a team’s conference record, we can use it to identify which teams had a significant disparity between their conference record as predicted by Net YPP and their actual conference record. I used a difference of .200 between predicted and actual winning percentage as the threshold for ‘significant’. Why .200? It is a little arbitrary, but .200 corresponds to a difference of 1.6 games over an eight game conference schedule and 1.8 games over a nine game one. Over or underperforming by more than a game and a half in a small sample seems significant to me. In the 2015 season, which teams in the SEC met this threshold? Here are the SEC teams sorted by performance over what would be expected from their Net YPP numbers.
Aha, he said. Suddenly there’s a little more to the perception of how the teams in the East finished. Here’s more from Matt:
… The two teams that vastly exceeded their YPP results also happened to meet in the SEC Championship Game. A confluence of factors allowed the Gators to win the SEC East in their first season under Jim McElwain. Florida finished 3-1 in one-score conference games, boasted the best in-conference turnover margin (+8), and scored three non-offensive touchdowns. For Alabama, the results are more mystifying. The Crimson Tide lost only once all season (by six points), and won just a single conference game by fewer than thirteen points. The Tide were not especially buoyed by turnover margin either, finishing a respectable, but hardly superb +1 in SEC play. However, the Tide did take advantage of unconventional touchdowns. They returned four interceptions for touchdowns in SEC play, including three against Texas A&M.
Georgia, in essence, was what ypp showed it was and nothing more. Richt didn’t exactly underachieve; however, Florida and Tennessee managed to overachieve. Alabama did, too, surprisingly. Are there lessons for Kirby to take from that and apply in Athens this season?