Everyone who has served a mission will understand what I am about to say:
Bronco reminds me of the kind of kid who came to the MTC that was a recent convert or had not been very active in the CHurch until recently. It was admirable he chose to come, but because he had no experience growing up in the Church he had no idea how to be a member (or missionary) and so he ACTED how he thought one should act. Usually this came across as the "ultra pious" or "holier than thou" type attitude. He tended to look down on any horsing around or goofing off as "Satanic" because he didn't understand that it was okay to let one's hair down every now and then.
I think Bronco is the same way. He has never been a "messenger for the Church" before and feels that having his switch always set on "preach" is what is required of him. Rather than be like LaVell was with your Dad (i.e. picking his spot when he would be spiritual with a player) Bronco is always shoving the missionary aspect of BYU down everyone's throats and, frankly, it gets annoying.
Much like the tpye of missionary I referred to, I understand what he is trying to do, but I find myself waiting for the time when he finally figures out it is okay to dial it down a notch.