Week 3 of the college football season was a bit odd.
At the top, almost nothing changed. Georgia, Alabama and Ohio State all looked the parts of top-three teams, and both Oklahoma and Michigan made resounding statements against overwhelmed competition (Nebraska and UConn, respectively). Ole Miss, an SP+ favorite, continued to back up its lofty ratings, and Clemson continued to win comfortably while looking as average as humanly possible on offense. Tennessee and Oklahoma State looked great on offense, Texas A&M and Iowa looked great on defense, and the world kept spinning on its axis.
Beneath the surface, however, were some pretty jarring results. Both the spread and SP+ whiffed mightily on games like Kansas-Houston (48-30 KU), Tulane-Kansas State (17-10 Tulane) and Eastern Michigan-Arizona State (30-21 EMU), and slight favorites such as Penn State (over Auburn), Washington (over Michigan State), Oregon (over BYU) and LSU (over Mississippi State) won far more comfortably than expected.
The result: a set of SP+ ratings that resemble Week 3 -- tranquil at the top and turbulent everywhere else. With preseason projections starting to phase out of the ratings a bit more quickly, and with Week 3's surprises, we saw 15 teams move up at least 10 spots in the rankings and seven move down by at least 10.
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. 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.