Championship/bowl games and just focus on regular season. For example, with Utah, their top games have incredible ratings, but that’s because those were the conference championships and a bowl game against Texas. My guess is their ratings would drop significantly if those are omitted.

Including bowl games and championships aren’t a true measure IMO, because a lot more people with no allegiance to either team are watching.

Also, I know this is really hard to control, but who a team plays matters a lot. For example, the B12 teams playing Texas and Okl every year gives them a huge boost, whereas BYU hasn’t been playing P5s with those types of followings in recent years.