Howell's resume would be slotted on their staff, and I guarantee the median wouldn't be anywhere near Defensive Coordinator. If you think my assessment of his resume is controversial or excessively pessimistic, I'm not sure what to tell you.
He may be 100% worthy of the job. And I'll be delighted if he is. But you're acting like skepticism is unreasonable, and that's beyond ridiculous. It's not driven by jealousy - I think I could hold my own against the guy in my own field. It's driven by my emotional investment in BYU's football team and my desire not to see a couple of seasons thrown away because of a bad coaching decision.
FTR - I think the risk here is pretty low, since Bronco is and will likely continue to be heavily engaged in the defense while Howell grows into the job.