College football Week 8 SP+ rankings

Finally, the best team in the country has played a game.

Based on its preseason projections, Ohio State has continued to rank first in SP+ for two months, and the Buckeyes certainly looked the part in an easy win over Nebraska on Saturday. The rest of the Big Ten slate, however, packed some surprises. Michigan, Wisconsin and Northwestern all looked fantastic -- Northwestern was super-fast and explosive! Northwestern! -- while Maryland, Michigan State and others were ... not great.

Combine that with some surprising Mountain West debut performances, and you've got a lot of movement in this week's ratings. Even if No. 1 remained the same.

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.