For this to make any sense, we need first to break down what the heck an F/+ rating is, and what it means. Here's the one-line version: Football Outsiders is trying to do to football what the Moneyball people did to baseball; they're creating stats that actually communicate the strength of a team. Regular football stats simply don't do this, and so Football Outsiders are on to something good. Read on, Frog fans.
*It's no joke-- I really did hear that saying from an Idahoan potato farmer in Minsk. He had many golden rhetorical tidbits, like, "If you walk a mile in another man's shoes, you're a mile away, and you have his shoes."
OK; the F/+ rating is a combination of two very separate stats, the FEI and the S&P. The what, you ask? FEI is "Fremeau Efficiency Index." A guy named Brian Fremeau analyzes thousands of college football drives every year, filtering out garbage time drives and clock-killing drives, etc. He takes the "real" drives, and figures out a national average for how likely a team is to score based on the starting yard-line for each drive. Mr. Fremeau figures out offensive and defensive averages. In his words,
"Offensive efficiency is then calculated as the total drive-ending value earned by the offenses divided by the sum of its offensive [Field Position Value] over the course of the game."
I also don't know what that really means, but offensive and defensive FEI (adjusted for the opponent's FEI) is nifty little stat.
The second component of the F/+ ranking is another combo stat, the S&P+, or a Success Rate measurement combined with a Points Per Play measurement (hence, "S&P"). The average S&P+ is 100.0. In their words,
"A boom-or-bust running back may have a strong yards per carry average and PPP, but his low Success Rate will lower his S&P. A consistent running back that gains between four and six yards every play, on the other hand, will have a strong Success Rate but possibly low PPP. The best offenses in the country can maximize both efficiency and explosiveness on a down-by-down basis. Reciprocally, the best defenses can limit both"
I do understand that; the plus sign on the S&P+ means each team's S&P score is adjusted for its opponents' strength. More opaque is the S&P+ breakdown for "standard downs" and "passing downs." The Football Outsider folks plays of certain down and distance measures to be "passing downs"-- 2nd and 8 or more, 3rd and 5 or more, and 4th and 5 or more. Some offenses don't fit this mold (like Oregon's) but TCU's probably does, as long as Mike Schultz isn't calling the plays.
So where are we-- the FEI is a measure of a team's efficiency based on field position; the S&P+ measures its success rate and explosiveness. Combine those two, and voila, you have the F/+ rating. The F/+ is Football Outsiders' best picture of, and predictor of, a team's success. For the 2005 through 2010 seasons, it was a better predictor of a college team's success than conference winning percentage, overall winning percentage, FEI by itself, and S&P+ by itself. It's the bottom line of college football stats.
And Football Outsiders has crunched TCU's 2011 drives and stats.
Last season TCU finished 17th in F/+. This is down quite a bit; in 2010 TCU finished 6th. The rise in TCU's recent F/+ ratings has been fueled by greatly increased offensive performance, while the defense has weakened in the last few years.
Football Outsiders' unofficial projection for TCU's 2012 F/+ is 21st nationally (13.9% over average).