Thursday, February 24, 2022

2021 Yards Per Play: Big 12

Time to check in on our fourth conference of the offseason, the Big 12. Prior to the 2021 season, there was some big news off the field, with Oklahoma and Texas opting to join the SEC sometime in the near future. While the Sooners and Longhorns are the flagship programs in the Big 12, the league showed its depth in 2021 as the Big 12 Championship Game was devoid of Sooner or Longhorn representation for the first time since 1998 and just the third time in the game's history

Here are the 2021 Big 12 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 Big 12 team. This includes conference play only, with the championship game not included. The teams are sorted 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 2021 season, which teams in the Big 12 met this threshold? Here are Big 12 teams sorted by performance over what would be expected from their Net YPP numbers.
Based on the .200 standard, no teams in the Big 12 significantly over or underachieved relative to their yards per play numbers. Baylor and Texas came close, but both didn't quite make the cut

The TCU Defense Hits Rock Bottom
Gary Patterson had a great run at TCU. During his two decades in charge, he built a mid-major power in Fort Worth and thanks to great timing, the Horned Frogs got called up to the majors when the Big 12 needed to replace some departing members. After being left for dead in the WAC when the Southwest Conference died in the mid-90's, the Horned Frogs have been in a major conference for a decade and they owe most of that to Patterson. However, for whatever reason, be it the empowerment of players, lack of scheme innovation, simply being in one place for two long, or something else, the 2021 TCU defense was the worst unit Patterson ever coordinated. The Horned Frogs allowed nearly 35 points per game (nearly 38 per game against FBS competition) and allowed more than seven yards per play to Big 12 opponents. You'll notice thanks to Kansas, they did not finish with the worst per play defense in the Big 12, but this was a unit that continuously blew assignments and gave up big plays. Is there hope for improvement in Fort Worth and Lawrence after both defenses posted such ghastly numbers in 2021? Read on to find out. 

Kansas and TCU (and Duke) joined a once rare, but growing subset of college football teams: those that allowed at least seven yards per play to conference opponents. Between 2005 and 2020, 25 BCS/Power 5 teams accomplished this ignominious feat. 
As you can see, with college football trending toward offense in scheme and rule enforcement, teams allowing more than seven yards per play is becoming more common. Between 2005 and 2011, a total of three BCS/Power 5 teams allowed more than seven yards per play to their conference opponents. Between 2012 and 2020, twenty-two did (along with three more in 2021). How did those previously porous defenses perform the next season? As with most extreme results, regression came a calling.
23 of the 25 teams improved their per play defense against conference foes the next season. Only Colorado in 2011 and Vanderbilt in 2019 saw their defenses play even worse the following season. On average, the 25 teams improved by nine tenths of a yard. While that may sound like a lot, remember, since they were allowing over seven yards per play, that meant on average their defenses were still bad, just not historically bad. TCU has a better track record than Kansas, especially on defense, so while both should improve defensively in 2022, I would expect TCU's to be more pronounced. I don't expect a return to their 2009 or 2010 form, but fielding a mediocre Big 12 defense is certainly within reason. 

Thanks for reading. Next week, we'll take a look at the Adjusted Pythagorean Record in the Big 12. And while this post pointed out a reason to be optimistic about TCU heading into 2022, next week's post will outline some a reason for pessimism. That's what we in the business call a tease. 

Thursday, February 17, 2022

2021 Adjusted Pythagorean Record: Big 10

Last week we looked at how Big 10 teams fared in terms of yards per play. his week, we turn our attention to how the season played out in terms of the Adjusted Pythagorean Record, or APR. For an in-depth look at APR, click hereIf you didn’t feel like clicking, here is the Reader’s Digest version. APR looks at how well a team scores and prevents touchdowns. Non-offensive touchdowns, field goals, extra points, and safeties are excluded. The ratio of offensive touchdowns to touchdowns allowed is converted into a winning percentage. Pretty simple actually.

Once again, here are the 2021 Big 10 standings. 
And here are the APR standings with conference rank in offensive touchdowns, touchdowns allowed, and APR in parentheses. This includes conference games only with the championship game excluded. 
Finally, Big 10 teams are sorted by the difference between their actual number of wins and their expected number of wins according to APR. 
I use a game and a half as a line of demarcation to determine whether or not a team significantly over or under-performed relative to their APR and by that standard, Iowa and Michigan State over-performed while Penn State and Nebraska under-performed. As it happens, Iowa, Michigan State, and Nebraska all saw their records differ from their expected records based on YPP as well and we went over some reasons for that last week, so we'll just take a quick look at Penn State. The Nittany Lions actually finished with a losing Big 10 record, dropping five of their last seven conference games. The usual suspects are to blame here as Penn State finished 1-4 in one-score conference games. In addition, their other Big 10 loss came by just nine points at Ohio State. 

Scott Frost's Track Record at Nebraska
Last week we identified Nebraska as the best BCS/Power 5 team (using Yards Per Play data) to finish with a single conference victory going back to at least 2005. Obviously, if you look at their APR numbers, they were probably one of the best one-win teams by that metric as well. I didn't want to completely rehash last week's post with a different metric, so I decided to take a closer look at how Nebraska has performed through the four seasons of the Scott Frost era and compare that performance to their peers. While I was looking through the data, I noticed Nebraska's significant under-performance in 2021 was not an isolated incident. In fact, the Huskers have underachieved more than any other Big 10 program (in conference play) since Frost's arrival in 2018 (at least relative to their Yards Per Play numbers). 
Here's a quick primer on how to read that table. In the past four conference seasons, Northwestern overachieved their expected win percentage (based on YPP) by an average of .172 per season. Prorated out to a nine-game conference schedule that equates to about an extra one and a half wins per seasons. Most teams are pretty close to zero in terms of their average over or under-performance. 11 of the 14 Big 10 teams have over or under-performed by less than one win per season. That's what happens as the sample size of seasons increases. Teams that overachieve one year tend to fall back to average or underachieve the next season. However, Nebraska seems to be a pretty significant outlier in that regard. The Huskers have underachieved on average by nearly .250! That is more than two wins over a full conference season. And while the Huskers were big time underachievers in 2021, that merely continued a trend that began in Frost's first season. 
The Cornhuskers have ranked in the bottom quartile in underachievement in each of Frost's four seasons in charge. They can't win close games (5-16 in one-score conference games under Frost) and they turn the ball over too much (-17 turnover margin in 35 conference games Frost has coached). Befitting that poor turnover margin, the Cornhuskers have won the turnover battle in just a quarter of the conference games Frost has coached (9) while committing more turnovers than their opponent nearly twice as often (17). Nebraska simply cannot be as unlucky as they were in 2021. They are destined to improve. But by how much? What is their ceiling? Their national title contending days are long over, but can they even compete for a division title? To do so in 2021, they will have to break a consistent streak of underachievement. 

Thursday, February 10, 2022

2021 Yards Per Play: Big 10

Hard to believe, but we are on to our third conference in the offseason previews. Let's take a look back at the Big 10. 

Here are the 2021 Big 10 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 Big 10 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 2021 season, which teams in the Big 10 met this threshold? Here are Big 10 teams sorted by performance over what would be expected from their Net YPP numbers.
Iowa and Michigan State, a surprise Big 10 Championship Game participant and a surprise NY6 Bowl participant significantly overachieved relative to their expected record based on YPP. Meanwhile, Nebraska underachieved by an historic margin (more on them later). Iowa rode their fantastic defense (second in Big 10 play in yards allowed per play), a sterling turnover margin (+9 in conference play), non-offensive scores (scored five non-offensive touchdowns in Big 10 play), and a great close game record (4-0 in one-score conference games) to a Big 10 West title. Michigan State was the inverse of Iowa, with a fantastic offense making up for a poor defense. The Spartans were also 4-0 in one-score conference games, allowing them to vastly exceed their expected record. And then there is Nebraska. The Cornhuskers were an amazing 0-7 in one-score Big 10 games. And their other Big 10 loss came by nine total points! Nebraska was doomed by inopportune mistakes. The Cornhuskers allowed five non-offensive touchdowns in Big 10 play while scoring none of their own. The five scores all proved decisive in close losses. A punt return touchdown allowed Michigan State to send their game with the Cornhuskers into overtime. A blocked punt touchdown allowed Iowa to stage a fourth quarter rally. A kickoff return touchdown was the difference in their loss to Wisconsin. Illinois returned a Taylor Martinez fumble for a touchdown in their Week Zero clash. And finally, Purdue returned a Martinez interception for a touchdown in their five-point win against Nebraska. If the game was close in 2021, Nebraska was going to blow it. 

Best One-Win Teams
Two weeks ago, we looked at Wake Forest and the worst BCS/Power 5 teams to finish conference play with exactly one loss. This week, in honor of Nebraska, let's look at the best one-win BCS/Power 5 teams. I mentioned earlier that Nebraska historically underachieved. It should come as no surprise then that they are the best one-win BCS/Power 5 team since 2005. 
The only other team that was even in the same neighborhood as Nebraska was the 2006 Illinois team coached by Ron Zook. If they know you by the company you keep, this probably does not bode well for Scott Frost. On the other hand, most of these teams saw significant improvement after their solid play/poor achievement seasons. 
Skip Holtz was the only coach that was unable to guide his team to an improved conference record the next season (and he was fired). The other four teams all saw significant improvement. Syracuse finished in a logjam at the top the Big East in their final season in the conference (and Doug Marrone used that as a stepping stone to an NFL head coaching gig). Michigan State bounced back from a rare losing season to win ten games. Washington State finished bowl eligible. And finally, Illinois garnered their first Rose Bowl appearance since 1983. Nebraska is almost destined to improve in 2022. A bowl bid should be the minimum requirement for Scott Frost to remain employed at his alma mater and if the Huskers have even the slightest bit of good fortune, they should be in contention for the Big 10 West division title. 

Thursday, February 03, 2022

2021 Adjusted Pythagorean Record: ACC

Last week we looked at how ACC teams fared in terms of yards per play. his week, we turn our attention to how the season played out in terms of the Adjusted Pythagorean Record, or APR. For an in-depth look at APR, click hereIf you didn’t feel like clicking, here is the Reader’s Digest version. APR looks at how well a team scores and prevents touchdowns. Non-offensive touchdowns, field goals, extra points, and safeties are excluded. The ratio of offensive touchdowns to touchdowns allowed is converted into a winning percentage. Pretty simple actually.

Once again, here are the 2021 ACC standings. 
And here are the APR standings with conference rank in offensive touchdowns, touchdowns allowed, and APR in parentheses. This includes conference games only with the championship game excluded (and the Wake Forest/North Carolina game also excluded). 
Finally, ACC teams are sorted by the difference between their actual number of wins and their expected number of wins according to APR.
I use a game and a half as a line of demarcation to determine whether or not a team significantly over or under-performed relative to their APR and by that standard, Louisville was the only ACC team that saw their record differ significantly from their APR. The Cardinals also undershot their record based on their YPP numbers and we went over a few reasons for that last week. 

Winning Seasons in Divisional Play
While I was overjoyed with Wake Forest winning their division and playing in the ACC Championship Game, i felt kind of sorry for NC State. The Wolfpack and Demon Deacons played a tight game in Winston-Salem, and for the seventeenth time in the last twenty meetings in this series, the home team won. Had the Wolfpack pulled the game out, they would have played in their first ACC Championship Game. Off the top of my head, I remembered a few other instances where the Wolfpack finished as the division runner-up. In 2017, the Wolfpack finished a game behind Clemson in the Atlantic Division of the ACC. They were unbeaten in ACC play when Clemson visited Carter-Finley stadium in early November. NC State led the Tigers at half, but lost 38-31. Had they held on to win, they would have represented the Atlantic Division in the ACC Championship Game. In 2010, NC State entered their regular season finale at Maryland needing a victory to tie Florida State at the top of the division and qualify for the ACC Championship Game by virtue of their head-to-head win against the Seminoles. Behind Russell Wilson, the Wolfpack jumped out to a 14-0 lead, but Maryland scored 38 of the next 41 points and withstood an NC State rally to win... wait for it...38-31. With those two instances seven years apart sticking out in my brain, I figured NC State would have by far the most second place division finishes in the ACC. Then I went and looked at the data. Aside from 2010, 2017, and 2021, NC State has finished with a winning conference record one other time since the ACC adopted divisions in 2005! The Wolfpack finished with a winning conference record in 2020, but since there were no divisions that season, I am not including it. With the NC State heartbreak angle not playing out as I had hoped, I decided to look at how often each team produced a winning ACC record since divisional play began in 2005. Excluding 2020, there have been seventeen seasons of divisional play in the ACC. Care to guess which team has finished with a winning conference record most often?
No real shock at the top of the standings. Clemson has not finished with a non-winning conference record since 2010, which was Dabo's second full season in charge. Other interesting statistical discoveries I made while conducting this research include:
  • Boston College had a run of five consecutive winning conference seasons from 2005-2009 under three different head coaches, but has not had a winning conference record since
  • Virginia has had three head coaches since 2005 and all three have posted exactly one winning conference season in that span
  • Despite competing with Butch Davis and Mack Brown, Larry Fedora is the only North Carolina coach to post a winning conference record and he did it three times
  • Since joining the ACC in 2013 and 2014 respectively, Pittsburgh and Louisville are in a five-way tie for second place with Florida State, Miami, and Virginia Tech for most seasons with a winning conference record (4) behind Clemson
Thanks for reading. Check back next week when we examine the Big 10.