In this week's Varsity Numbers, Bill Connelly revisits some measures and concepts: Adjusted Scores, Covariance, and momentum (or whatever you choose to call it).
11 Jan 2012
by Brian Fremeau
The college football season abruptly concluded on Monday night with the Alabama Crimson Tide turning in the best game performance of the year. They deserve every bit of the celebration that has followed, and there’s no asterisk on the national championship as far as I’m concerned. Now, I’ll try to explain why Alabama ranks third in FEI and why I’m not putting an asterisk on that either.
Since I started working with FEI data in 2003, the rating system has consistently agreed with the consensus regarding the national champion. Though there have been frequent arguments about the teams given the opportunity to play in the two-team BCS championship format, the team hoisting the crystal football at the end of the year has always had a legitimate claim to the nation’s best end-of-year resume as well. The BCS system rewards the "best overall season," a distinction from playoff formats that reward the "best end-of-year run."
Of course, any team can be beaten on any given day. LSU’s distinction of having had the best overall season heading into the championship didn’t make them invincible, and I never claimed otherwise. What I’ve been wondering about in the aftermath of their loss in the title game is: do they still own the nation’s best overall season? The final FEI ratings support that claim.
I knew this kind of scenario would happen eventually. It’s happened before, of course. I don’t have FEI data for 2002, but I wouldn’t be surprised if the system considered the Miami Hurricanes to have had the better overall season despite a loss to the Ohio State Buckeyes in overtime in the championship. I’ve long thought that the Notre Dame Fighting Irish were likely the nation’s best team in 1989 and the second-best team in 1988, even though the on-field results in those seasons suggest the opposite.
It takes a particularly unique set of circumstances to win a national championship. According to FEI, this year’s LSU Tigers were significantly better than the 2007 and 2003 Tigers that did win the title. Neither of those teams had to face a team rated as highly as Alabama even once, while this year’s edition faced the Tide twice, both away from Baton Rouge. The Oregon game this year (also away from home and LSU’s third-toughest test according to FEI) would be the equivalent of the toughest opponent LSU faced in 2003 or 2007. The Tigers finished this year with the No. 1 strength of schedule and won 12 FBS games.
However, they didn't win when it counted most. In fact, they barely competed. The other two teams in the conversation, Alabama and Oklahoma State, were undefeated in regulation (a claim that helped vault LSU fortuitously into the 2007 championship game). The Crimson Tide's only loss to LSU trumped Oklahoma State's loss to Iowa State to position Alabama for the rematch, but the win column heavily favored the Cowboys. Alabama only played three FEI top-30 opponents, winning two, while Oklahoma State posted seven such victories. Only by playing the FEI No. 1 twice did Alabama's schedule edge out that of the Pokes.
Here are the top-to-bottom resumes of LSU, Oklahoma State, and Alabama according to GFEI, opponent-adjusted single-game efficiency.
|Alabama GFEI Resume||LSU GFEI Resume||Oklahoma State GFEI Resume|
|LSU||W 21-0||.912||1||Alabama||W 9-6||.716||7||Oklahoma||W 44-10||.872||2|
|Florida||W 38-10||.588||22||Oregon||W 40-27||.670||11||Baylor||W 59-24||.766||4|
|Vanderbilt||W 34-0||.582||24||West Virginia||W 47-21||.608||17||Texas Tech||W 66-6||.710||9|
|Arkansas||W 38-14||.572||27||Mississippi||W 52-3||.586||23||Missouri||W 45-24||.505||50|
|LSU||L 6-9||.513||48||Georgia||W 42-10||.565||29||Stanford||W 41-38||.455||73|
|Penn State||W 27-11||.459||72||Auburn||W 45-10||.562||32||Tulsa||W 59-33||.450||76|
|Tennessee||W 37-6||.398||125||Arkansas||W 41-17||.560||33||Texas A&M||W 30-29||.420||99|
|Auburn||W 42-14||.337||181||Tennessee||W 38-7||.403||120||Texas||W 38-26||.409||112|
|Mississippi||W 52-7||.311||207||Florida||W 41-11||.389||136||Kansas||W 70-28||.320||192|
|Mississippi State||W 24-7||.281||246||Alabama||L 0-21||.317||198||Kansas State||W 52-45||.315||201|
|North Texas||W 41-0||.032||688||Mississippi State||W 19-6||.313||206||Arizona||W 37-14||.156||446|
|Kent State||W 48-7||-.082||900||Western Kentucky||W 42-9||.152||453||Iowa State||L 31-37||.035||681|
|Kentucky||W 35-7||.139||473||Louisiana Lafayette||W 61-34||.033||685|
Alabama's final game was the most impressive victory of the year without a doubt. Based on that performance, I have tremendous confidence that the Crimson Tide would also have navigated the tougher schedules of Oklahoma State and LSU just as successfully as those two teams did. However, FEI doesn't have the data to back up that confidence. Alabama didn't play those games.
I've always been convinced that a computer rating system cannot be much more than a lens to help us focus on the big picture. We can continue to work to improve our metrics, collect more and better data, and make that big picture even more clear. But the role of FEI isn't to crown a national champion. In years in which FEI and the national championship game result agree, it can be tempting to insist that the ratings mean more than they do. This year is a good reminder to not fall into that trap.
The tables below represent the best single-game performances in Offensive FEI, Defensive FEI, and overall Game FEI of the 2011 season. It is important to note that the individual OFEI, DFEI and GFEI data points are subjected to a relevance factor when calculating the season-long OFEI, DFEI and FEI team ratings. Oklahoma State, for instance, had three of the top-10 GFEI performances of the year, but the result against Texas Tech receives very little weight in Oklahoma State's overall FEI rating.
|Offensive FEI Single-Game Performances of the Year|
|2.550||10/8||Alabama||vs. Vanderbilt||48||W 34-0|
|2.472||9/17||Navy||at South Carolina||7||L 21-24|
|2.424||10/1||Arizona||at USC||29||L 41-48|
|2.423||10/15||Texas A&M||vs. Baylor||86||W 55-28|
|2.421||10/8||Miami||at Virginia Tech||31||L 35-38|
|2.359||9/10||Tennessee||vs. Cincinnati||30||W 45-23|
|2.322||10/22||Houston||vs. Marshall||67||W 63-28|
|2.321||11/19||Baylor||vs. Oklahoma||12||W 45-38|
|2.309||1/2||Stanford||vs. Oklahoma State||3||L 38-41|
|2.246||10/29||Oklahoma||at Kansas State||19||W 58-17|
|Defensive FEI Single-Game Performances of the Year|
|-2.606||10/29||Oklahoma State||vs. Baylor||1||W 59-24|
|-1.879||1/9||Alabama||vs. LSU||17||W 21-0|
|-1.877||12/3||Oklahoma State||vs. Oklahoma||18||W 44-10|
|-1.719||11/19||South Florida||vs. Miami||3||L 3-6|
|-1.658||11/19||North Carolina State||vs. Clemson||22||W 37-13|
|-1.525||10/1||Boise State||vs. Nevada||38||W 30-10|
|-1.511||11/19||Rutgers||vs. Cincinnati||25||W 20-3|
|-1.441||10/22||Miami||vs. Georgia Tech||16||W 24-7|
|-1.413||11/5||Alabama||vs. LSU||17||L 6-9|
|-1.367||10/7||Boise State||at Fresno State||44||W 57-7|
|FEI Single-Game Performances of the Year|
|0.912||1/9||Alabama||vs. LSU||1||W 21-0|
|0.872||12/3||Oklahoma State||vs. Oklahoma||4||W 44-10|
|0.779||10/29||Oklahoma||at Kansas State||18||W 58-17|
|0.766||10/29||Oklahoma State||vs. Baylor||29||W 59-24|
|0.738||1/4||West Virginia||vs. Clemson||32||W 70-33|
|0.729||11/12||Oregon||at Stanford||7||W 53-30|
|0.716||11/5||LSU||at Alabama||3||W 9-6|
|0.714||9/17||Wisconsin||vs. Northern Illinois||53||W 49-7|
|0.710||11/12||Oklahoma State||at Texas Tech||77||W 66-6|
|0.699||10/21||Syracuse||vs. West Virginia||17||W 49-23|
We're not going to put together our projections for the 2012 season until recruiting and spring practice wrap up, but as has been the case in year's past, the foundations for next season expectations are formed in previous year data. I've already updated the 2011 Program FEI ratings, a five-year weighted drive efficiency metric that forms the core of my annual FEI projections. Below, I've plotted out each of the drive unit metrics I measure and their correlations to both same-season winning percentage and correlations from year-to-year. Light blue plots actually represent a negative correlation to win percentage, but are plotted as a positive correlation to allow for easier comparisons.
The Fremeau Efficiency Index (FEI) rewards playing well against good teams, win or lose, and punishes losing to poor teams more harshly than it rewards defeating poor teams. FEI is drive-based, not play-by-play based, and it is specifically engineered to measure the college game.
FEI is the opponent-adjusted value of Game Efficiency (GE), a measurement of the success rate of a team scoring and preventing opponent scoring throughout the non-garbage-time possessions of a game. FEI represents a team's efficiency value over average. Strength of Schedule (SOS) is calculated as the likelihood that an "elite team" (two standard deviations above average) would win every game on the given team's schedule.
Mean Wins (FBS MW) represent the average total games a team with the given FEI rating should expect to win against its complete schedule of FBS opponents. Remaining Mean Wins (FBS RMW) represent the average expected team wins for games scheduled but not yet played.
Offensive FEI (OFEI), Defensive FEI (DFEI), Special Teams Efficiency (STE) are also provided, along with Field Position Advantage (FPA), the share of the value of total starting field position earned by each team against its opponents.
Only games between FBS teams are considered in the FEI calculations. These FEI ratings are a function of results of games played through January 9. The ratings for all FBS teams can be found here. You can also find OFEI, DFEI, and STE on their own pages.
43 comments, Last at 08 Dec 2012, 3:41am by john123456