partially for the reasons you stated about him running the "Whittingham's system." He has very little experience outside of Utah and for all the same reasons people are screaming at the promotions of Doman and Howell I think it could turn out the same for him.
Speaking of systems. Bronco has a system. Whittingham has a system. The problem at BYU is that we don't have the talent currently to run Bronco's system. Whittingham has been able to gather enough talent to make his system work for well over a decade. Bronco tried to plug and play with Howell, much like Whittingham did with Sitake. The difference is that Utah has better defensive talent year in and year out, while BYU has been very up and down.