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 intended to be predictive and forward-facing. That is important to remember. 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.

There wasn't much major movement in this week's SP+ top 10 -- Florida and Auburn rose a little bit, while Penn State dropped a few spots after struggling for a half with Buffalo.

A couple of Pac-12 teams made noteworthy moves, though. First, Oregon rose from 24th to 14th after absolutely humiliating a Nevada team that had just beaten Purdue. Meanwhile, Washington fell from eighth to 21st after letting Cal pull an upset for the second straight year. That flip means Oregon is now the Pac-12 North favorite -- the Ducks' projected conference win total is 6.5, compared to Washington's 6.2 and Washington State's 5.8.

There was some noteworthy non-movement, as well. Both Maryland and North Carolina have surprised early in the season -- Maryland by scoring a combined 142 points in its first two games (both easy wins) and UNC by pulling upsets of both South Carolina and Miami. SP+ isn't overreacting, though: Maryland has moved up from 68th in the preseason to 38th, while UNC has gone from 66th to 56th. Each's team's odds of reaching bowl eligibility, however, have soared -- UNC's gone from 26 percent to 82, Maryland from 27 percent to 79.