There is no question that Kirby can't and doesn't develop QB's. I mean, he's a defensive coach by background and training. His QB development will depend on the offensive coaches he hires. Which is a problem, because guys who show they can develop QB's are very hot commodities and move on quickly. But Mullen, who is the QB developer himself, doesn't have to worry about that. And he attracts higher quality offensive assistants, because while he is developing QB's, he is also teaching the assistants how to develop QB's.
So Kirby better never miss on his offensive coaching hires.