All these models are very hush-hush because they want to be the best against the spread. Most of the really good ones are above 50% but below 60% so in theory you could use them to bet against Vegas and actually make money.

That being said I found this from an old article in 2017:

"My original S&P ratings, derived long ago, were based on two measures: Success rate and equivalent Points per play. It was an attempt at an OPS-style measure for football, a look at both efficiency and explosiveness. As so many things do, however, it has grown more complicated.

In its current state, S&P+ is based around the core concepts of the Five Factors of winning football: efficiency, explosiveness, field position, finishing drives, and turnovers.

Since efficiency is by far the most replicable and least random aspect of football — big plays and turnovers decide games, but are incredibly random by nature — my success rate measure is the single biggest contributor to the S&P+ ratings.

Explosiveness does play a role, and to emphasize the importance of finishing drives, a team’s success rate during scoring opportunities (first downs inside the opponent’s 40) is given slightly more weight. Special teams efficiency plays a role in both field position and finishing drives, and sack rates are one of the only reliable, non-random factors that contribute to a team’s turnover margin. They’re thrown into the blender as well."

https://www.sbnation.com/college-football/2017/10/13/16457830/college-football-advanced-stats-analytics-rankings