Love this question... I think 8-4 is almost the floor most years if you lose all of the games where you face a true peer, and 1 upset. So if you gave me a random FBS Coach for this year I would say 9-3 is most likely record with a vast most of the data points being exactly 9 or 10.
How many games would a random coach in the FBS Jason Candle, Chip Kelly win at Ohio State every year? They're never not going to rank less than top 7 in recruiting, SOS mid 50s, NIL budget top 10. How much difference does Ryan Day make in your opinion?