The 2021 college football season was an odd one for computer ratings.
On one hand, despite all the quirks of 2020's COVID-19 season, the effects of the transfer portal and an early-starting coaching carousel, etc., the game itself wasn't too much harder to project than normal. Using absolute error -- the average difference between projections and reality -- the top 10 performing systems at ThePredictionTracker.com (including only systems that projected every game and not including variations of the line itself) missed the average college football game by 13.0 points per game this season. This average will likely increase at least a hair during the typically volatile bowl season, but considering that average jumped from 12.6 in 2018-19 to 13.4 in 2021, 13.0 represents a nice settling-in toward normality.
Performance against the spread, however, dropped considerably. It has for a while now because the spread itself appears to be getting better and better. While these top 10 systems averaged 52.4% against the spread in 2018, that number sank to 50.9% in 2019, 50.4% in 2020 and a dismal 48.4% in 2021. Among the 33 systems that projected every game, only five ended up over 50% this year; none were over 51%. In 2019, 20 of 44 were at 51.2% or higher.
Fortunes for my SP+ ratings have been no different. SP+'s absolute error was a solid 13.0 points per game as well, and if offered, I'd have absolutely taken that at the beginning of the year because of all the uncertainty. But that was good for only 48.4% against the midweek spread. If you compare its performance to the closing line and include FBS-versus-FCS games (which I don't believe are included at Prediction Tracker), you get up to 52.1% for the season. But that's a far cry from 2019, when it hit 53.4% ATS in FBS-versus-FBS games alone.
The sportsbooks always catch up, and they certainly seem to have absorbed some of the success of the better projection systems out there. But we still have FBS-versus-FCS games and, above all else, we still have win totals. For now.
The books haven't caught up to SP+ on win totals (yet)
Give it time, of course. But flashing back to August's win projections, you could have made a lot of money following SP+'s lead.
If you had bet on every team based on SP+'s win projections, no matter how close the projections and Caesars Sportsbook were to each other, you would have won 60.4% of your bets -- it went 75-48-7 overall. It won 61.9% of its under picks and 59.0% of its overs.
When the disagreement was pretty large, so was SP+'s win percentage.
When it projected a total at least 1.0 win off of the Caesars total, it went 16-5-2 (74%).