College football SP+ rankings after Week 7

While things seem as uncertain as ever in the college football polls, with as many ranked teams losing per week as ever before, on paper we're starting to see wheat separating from chaff. In this week's SP+ ratings, the No. 2 and No. 4 teams in FBS are separated by 6.3 points -- nearly the same distance that separates No. 4 from No. 14 and No. 16 from No. 43. We know who the best teams should be moving forward, even if only one top team has managed to avoid a defeat so far.

What is SP+? In a single sentence, it's a tempo- and opponent-adjusted measure of college football efficiency. I created the system at Football Outsiders in 2008, and as my experience with both college football and its stats has grown, I have made quite a few tweaks to the system.

It is, as always, important to note that SP+ is intended to be predictive and forward-facing. It is not a résumé ranking that gives credit for big wins or particularly brave scheduling -- no good predictive system is. It is simply a measure of the most sustainable and predictable aspects of football. If you're lucky or unimpressive in a win, your rating will probably fall. If you're strong and unlucky in a loss, it will probably rise. It is a look at how teams should likely perform moving forward.