Below are the current SP+ rankings, last updated after the games of Oct. 4.
What is SP+? In a single sentence, it's a tempo- and opponent-adjusted measure of college football efficiency that I originally created at Football Outsiders in 2008. SP+ is intended to be predictive and forward-facing. It is not a résumé ranking, so it does not automatically give credit for big wins or particularly brave scheduling -- no good predictive system does.
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.