Along those lines, conferences adding the top teams from other conferences (USC, UCLA, Texas, Oklahoma) is going to water down the number of wins by top teams. You can't take the top teams from 2 different conferences and expect them all to go 11-1 or better. That just isn't going to happen.
But if you remove those top teams from other conferences then you are going to get 12-0 TCU and 11-1 Baylor, 11-1 Oregon or Washington, for example. The SEC and Big 10 just stole their likely 1.75 losses per remaining team by removing 2 of the top teams of their conference.