That there is not pressure to win at BYU.
Think about Ohio State, or Alabama. They are big time and there is major pressure from outside and inside school to win now. Thus you see when the QB isn't playing up to expectation, they put the next guy in. In Alabama's case it is that Freshman Jalen Hurts. At OSU Braxton Miller got replaced by Cardel Jones.
Those coaches and coordinators demand athletes are the best on the field and if not, they replace them because if they don't, it will be the coach's heads that roll.
Clearly, there is and probably never has been that type of pressure at BYU and thus Taysom is QB while a better QB sits behind him.