Doman could absolutely have moved elsewhere when his stock was high after the '09 season. He'd placed two QBs in the pros in 4 years and BYU had won 43 games. Could he have gone elsewhere as an OC? Maybe not, but certainly as a QB coach at a bigger school.

Anae did essentially what DC is doing now after being fired at BYU- go to a BCS school as an OL coach and running game coordinator.

And I know for a fact that Bronco could have left BYU three years ago, for a significant pay raise, to UCLA.

And none of this addresses the fact that just like any other job, assistant coaches generally express interest before being pursued. They might get a phone call via networking saying the job is open, but often they call, express interest, and send their resume in just like anyone else. None of that happens if your (predominately LDS) coaches like coaching at BYU/living in Utah and aren't keen on moving just for a promotion.