Sure, BYU will likely lose a few this year. But isn't the point of going Independent the opportunity to make the big splash?
I give BYU maybe a 15-20% chance to beat Michigan State on the road this season with Tanner at QB. With Taysom? 35-40%. The chance of winning against Boise State, Utah, Mississippi State, and UCLA would all go up in similar increments. These teams simply can't pin their ears back and come after Taysom the way the can with Tanner. And in the secondary they can't just tell their DBs to lock down the WRs and have the game be over, ala Michigan last season. For all the grief Tanner gets for that game, only a small part of the lack of success on offense was attributable to him. Simply having Taysom on the field would've given BYU a shot in that game because Michigan could not have employed the same defense without Taysom gaining huge yardage on the ground.
Mich St, Miss St, Utah, and UCLA all play that similar style of defense.