The college football gods threw us curveball after curveball in Week 12. Favorites struggled. Turnovers determined huge games. Teams overcame statistical deficiencies to win games with long snapper touchdowns. South Carolina saved an entire season's worth of good offense for one game and blew out CFP contender Tennessee.
SP+ took in all this chaos and said, "No, I think I've got it about right." While teams' ratings changed here and there (Tennessee's fell, as you would expect) the top five teams remain the same in this week's rankings, and we've got only one new team entering the top 10: Clemson, which jumped from 14th to 10th.
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.
SP+ is indeed 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.