The offense was awful to watch the first two years. Taysom and Williams and a couple others bailed the offense out EVERY GAME. The defense was good. The offensive staff was not prepared for D1 football. Also, Sitake made culture mistakes — departing from Bronco's discipline culture. It truly showed up the second season. In the third season, things looked MUCH better, but far from perfect. There were small mistakes that cost BYU 4 games (BSU, NIU, Cal and even UU).
You're (in theory) a smart guy and may have watched the games. You may have played sports. I'm sure you can look a little deeper.