Caesars by William Hill lists Alabama as an eight-point favorite over Ohio State in Jan. 11's national title game. SP+, however, sees something a little closer. With bowl season in the books, it gives Nick Saban's Crimson Tide a 4.3-point advantage over Ryan Day's Buckeyes.
This is a tricky game to evaluate. On one hand, Alabama was one of the biggest overachievers of the season in terms of SP+ projections. Even though they rank a distant first overall, the Tide have still overachieved projections by an average of 9.7 points per game. That the line gives them more of a cushion, then, makes sense.
On the other hand, SP+ liked Ohio State far more than the market did before the Buckeyes' dominant performance against Clemson. That it likes them more than the market makes sense, too.
We've got eight more days until we find out which impression is correct.
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.
We got a slight, if flawed (considering the opt-outs), opportunity to compare conferences to each other during bowl season. That, combined with a bit of self-assessment, created quite a bit of movement.
UP: SEC and Big Ten teams
I got a chance in recent weeks to use previous seasons as guinea pigs of sorts. I basically created 2020-esque schedules (no nonconference games for SEC, Big Ten and Pac-12 teams, single nonconference games against lower-level teams for the ACC and Big 12) for 2018 and 2019, then compared the resulting SP+ ratings to what the actual full-season ratings were for that season. That offered me a glimpse at how much I should be weighing different factors to produce the most accurate possible rating this time around.
What I found was that I should be weighting preseason projections a bit more (they're always in the ratings, but they're mostly phased out by the end of the year) and not assigning an overt amount of weight on the minimal nonconference games we actually saw. An unsatisfying conclusion? Absolutely -- we want what our eyes just saw to matter a ton. But I shifted weights a bit in the name of attempted accuracy. And it resulted in quite a few SEC and Big Ten teams making jumps.
In the SEC, Mississippi State combined this on-paper boost with a solid showing against Tulsa to jump 23 spots from 81st to 58th. Ole Miss jumped from 48th to 35th, and while this shift in weighting only impacted teams by a few points, it was enough to also boost non-bowl teams like LSU and Tennessee into top-50 positions.
The Big Ten got a similar boost, most personified by Penn State. The Nittany Lions went a dramatically unlucky 4-5 in the regular season -- their losses to Indiana and Nebraska both featured extremely high postgame win expectancies, meaning they would have won far more often than not -- and they looked mostly strong in their season-ending four-game winning streak. But despite opting out of bowl season, they jumped from 28th to 17th because of the Big Ten's overall rise.
DOWN: Notre Dame
As I've written before, postgame win expectancy takes the stats from a given game, tosses them into the air and says, "With these stats, you could have expected to win this game X% of the time." Despite losing by a semi-respectable 17 points to Alabama in the Rose Bowl, the Irish didn't impress SP+. Before garbage time criteria kicked in with the Tide up 31-7, Notre Dame produced just a 35% success rate to Bama's 64% and got dwarved from a big-play perspective. Toss in some red zone failures, and what does that produce? A postgame win expectancy of 0.002%, equivalent to a scoring margin of minus-38.9. That came on the heels of a 0.009% postgame win expectancy against Clemson (equivalent to a 34-point loss).
Combined with a slight downgrade for the ACC as a whole thanks to an awful bowl season and the above-mentioned weighting adjustments, Notre Dame ended up plummeting in SP+. After rising to fourth after their 10-0 start, they are now 16th. Bama and Clemson both treated them like they were Vanderbilt, and SP+ responded in kind.
Again, SP+ is a predictive rating, not a résumé rating. SP+ is saying that if No. 16 Notre Dame and No. 17 Penn State each played 162-game seasons, they would prove about equal to each other. It's not saying the Nittany Lions had as good a year as the Fighting Irish -- they clearly did not. Notre Dame flashed a pretty high ceiling in its first 10 games, but the dramatically low floor of the last two games altered impressions considerably.
