by Brian Fremeau

At last, we have arrived at the middle of October. We have finally shed all preseason projection data and can examine the 2009 college football season through a clean lens. 342 FBS vs. FBS games have been played to date. From this point forward, only those games are considered. How well have teams played?

There are two key components to that question. The first is answered by Game Efficiency, the raw assessment of a team's scoring efficiency over the non-garbage possessions of a game. The second requires context: How efficient was each team relative to the strength of its opponents? Now that the noise of preseason projected data has been filtered away, we can examine the FEI methodology as it relates to that question for offenses, defenses, and entire teams.

There may be no better week to introduce this year's adjusted Offensive FEI and Defensive FEI metrics for the first time. According to the latest FEI ratings, a top-5 offense played a top-5 defense twice in Week 7, the first such occasions of the 2009 football season. On Thursday night, Cincinnati's No. 3 offense defeated South Florida's No. 5 defense. On Saturday, USC's No. 2 defense stopped Notre Dame's No. 1 offense in a dramatic finish. Obviously, the game outcomes were influenced by many factors, plays, and drives, but can we isolate these particular unit performances?

Cincinnati possessed the ball 14 times in non-garbage play, scoring four touchdowns (on drives of 3, 84, 74, and 70 yards) and kicking two field goals. The Bearcats attempted a third field goal from the 23-yard line, punted six times and threw one interception. With Cincinnati's starting field position, an average offense against an average defense would expect to score 27.9 points. Cincinnati's offense earned 34.6 points of drive-ending value (four touchdowns and three field goal opportunities). The Bearcats' raw Offensive Efficiency (OE) for the game was .239, or 24 percent greater than average.

Notre Dame possessed the ball 11 times in non-garbage play, scoring four touchdowns (on drives of 56, 78, 68, and 13 yards) and attempting no field goals. With their starting field position, an average offense would expect to score 22.0 points. Notre Dame earned 27.8 points of drive-ending value, producing an OE of .276.

The USC and South Florida defenses have held teams well below average scoring expectations this year, and we run the raw OE numbers through several adjustment iterations to determine a recalibrated Offensive FEI (OFEI) rating for the game. Notre Dame's OFEI against USC was 1.570 (roughly 160 percent stronger than average); Cincinnati produced an OFEI of 1.372. Reciprocally, the performances of the USC and South Florida defenses should be measured against the prolific scoring expectations of the high-powered Notre Dame and Cincinnati offenses. USC produced a Defensive FEI (DFEI) rating of -1.263 (roughly 130 percent stronger than average); South Florida produced a DFEI rating of -.972.

Note that strong offensive efficiency produces a rating above zero and strong defensive efficiency produces a rating below zero. Also note that offensive and defensive efficiency are calibrated in each adjustment iteration for the purposes of equivalency. Since the best offenses can be much more prolific than the best defenses in terms of raw efficiency, standard deviations are used to balance the scales of offensive and defensive data. Thus, it may be accurate to describe Notre Dame's offense as having played roughly 160 percent stronger than average against USC, and USC's defense as having played roughly 125 percent stronger than average against ND -- but the two terms are not directly comparable.

Notre Dame's offensive performance was the sixth-best of the season in college football; Cincinnati's ranked 19th. USC's defensive performance was eighth-best of the season in college football; South Florida's ranked 34th. Table 1 lists the top 5 in each category over the first 342 games of 2009.

Remember that the actual FEI ratings for all teams include an additional "relevance of data" factor and are not a simple average of each team's cumulative OFEI and DFEI data. Performances against stronger competition, win or lose, is rewarded, but dominant performances against weak competition receives less relevance weight in the formula.

Week 7 FEI Top 25

The principles of the Fremeau Efficiency Index (FEI) can be found here. Like DVOA, FEI rewards playing well against good teams, win or lose, and punishes losing to poor teams more harshly than it rewards defeating poor teams. Unlike DVOA, it 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. Like DVOA, it represents a team's efficiency value over average. Strength of Schedule (SOS) is calculated as the likelihood that an elite team would win every game on the given team's schedule. New This Week: SOS is calculated only from games already played, and does not include future games scheduled.

Only games between FBS teams are considered in the FEI calculations. Preseason projections are no longer included in the calculations. FEI ratings are a function of results of games played through October 17th.

FEI ratings for all 120 FBS teams are now listed in the stats page section of FootballOutsiders.com. Click here for current ratings, or here for 2008 ratings.

Posted by: Brian Fremeau on 21 Oct 2009

6 comments, Last at 23 Oct 2009, 9:49am by Brian Fremeau