1 - He understands how to develop the discipline and culture of a team to add wins and quickly turn a down program into a consistent program.
2 - He knows defense, how to call plays, and (perhaps most importantly) how to take the talent he has and get the absolute most out of it on the defensive side of the ball. His teams outperform their talent/athleticism almost every year.
3 - His players seem to consistently respect him. They may get frustrated and not agree with everything, but they respect him and play the way he asks them to play.
Of course, Bronco isn't among the elite head coaches in college football because of some other flaws (doesn't hire great, has offensive issues consistently, etc.) and doesn't give fans warm fuzzies. But he is a great coach and perfect for the situations he inherited both at BYU and UVA.