## Wednesday, April 05, 2017

### 2016 Yards Per Play: Mountain West

This week, we examine the Mountain West Conference. Here are the Mountain West standings.
So we know what each team achieved, but how did they perform? To answer that, here are the Yards Per Play (YPP), Yards Per Play Allowed (YPA) and Net Yards Per Play (Net) numbers for each Mountain West 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.
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. It would be fantastic if college football teams played 100 or even 1000 games. Then we could have a better idea about which teams were really the best. Alas, players would miss too much class time, their bodies would be battered beyond recognition, and I would never leave the couch. 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 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 under-performing by more than a game and a half in a small sample seems significant to me. In the 2016 season, which teams in the Big 10 met this threshold? Here are Mountain West teams sorted by performance over what would be expected from their Net YPP numbers.
2016 was a unique year for the Mountain West as nearly half the league saw their actual record differ from their predicted YPP record. Air Force, New Mexico, and Wyoming exceeded their expected record while Fresno State and Utah State fell well short of theirs. Air Force, New Mexico, and Wyoming combined to go 11-3 in one-score conference with each team making just enough plays in crunch time to produce 17 conference wins between them. Air Force and New Mexico also did a great job of using their unique offenses to minimize their per play differential. The Falcons and Lobos keep the ball on the ground for the most part with their option based attacks. Air Force ran the ball more often than any team in 2016 and New Mexico was fourth in run plays per game. Their methodical offenses allowed them to beat their opponents with volume. Air Force ran about seven and a half more plays per game than their conference opponents and New Mexico ran nearly five more plays per game than their Mountain West foes. New Mexico was particularly adept at using their offense to hide their bad defense as the Lobos defense faced about seven fewer plays per game than the average Mountain West team. Fresno State and Utah State can blame bad luck in close games (combined 0-7 in one-score conference games) and turnovers (last and second to last in turnover margin in conference games) for their poor league records. You can also use the 2016 Mountain West as the counterpoint to the ‘defense wins championships’ narrative. Air Force, New Mexico, and Wyoming each finished below average on defense in the Mountain West, with Wyoming and New Mexico finishing second to last and last respectively, but combined to go 17-7 in league play. Meanwhile, Utah State and Fresno State finished third and fourth in the conference in yards allowed per play, but the lone conference win they combined for came when they played each other.

Regression may be in store for Wyoming in 2017 and not just because they were not quite as good as their record in 2016. The Cowboys may ride headfirst into the Plexiglass Principle. Bill James is usually given credit for coining the phrase which holds that teams that drastically improve in one season tend to decline the next season. Wyoming drastically improved in 2016, going from two conference wins in 2015 to six and a division crown. To ascertain what we might expect from the Cowboys in 2017, I looked at all mid-major teams since 2005 that saw their conference win total increase by at least four games from one season to the next and looked at how they did in conference play in the follow up season. The results are summarized in the table below.
Twenty two teams met the criteria of improving by at least four conference games and those twenty two teams proceeded to lose about half of their gains the next season. Collectively, teams combined to win about 1.7 fewer conference games. Sixteen teams saw their win total decline, four teams saw their win total remain the same, and only two improved. Perhaps more troubling for Wyoming fans is that more than a third of the twenty two teams (eight) saw their conference win total decline by three or more games. The Mountain Division is quite strong, so if Wyoming gets back to the Mountain West Championship Game, Craig Bohl should definitely be the coach of the year.