College football SP+ rankings after Week 13: Clemson moves up, the committee's BYU mistake and more

The biggest superpowers of the late-2010s are distancing themselves in 2020. Alabama and Clemson, winners of the 2015-18 national titles (among others, in the Tide's case), both looked spectacular on Saturday and inched further ahead of the pack in the SP+ ratings. They beat Auburn and Pitt (22nd and 34th in SP+ last week, respectively) by a combined 94-30, and they each gained about two adjusted points per game in the SP+ ratings. With Ohio State sidelined, the Tide and Tigers are now a semi-distant No. 1 and No. 2.

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.

More than ever, it's important to note that 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.

Those last two sentences are key. Week 13 might not have been the normal Rivalry Week in any way, shape or form, but it produced Rivalry Week-esque twist results.