Yes he's got a decent winning percentage but he has beaten very few good teams. That isn't a reason to dislike him personally though but it is a reason to be dissatisfied with his coaching. But the personal dislike as come about because of his remarks and behavior towards the fans. He has made many disparaging remarks about BYU fans over the years and has never hidden his contempt towards us. Why should we personally like or support the guy when he insults and dislikes us?
Let me let you in on a little truism. If bronco can go 12-1 or 11-2 consistently then he can insult and despise me all he wants. But he doesn't get to go 7-6 and then 8-5 year, after year, after year, and then treat me like I'm an imbecile who knows nothing and then get my undying support.