I've been thinking about this and trying to make sense of it. What I keep coming back to is the old saying, "People don't quit jobs; they quit bosses." As much as these guys seem bigger than life, it has to come down to a lot of the things us unwashed deal with. If you hate getting up in the morning and coming to work because of your boss (or whatever), a change is in order. No way Painter makes a decision like this without due consideration, prayer and probably a stretch of time where he hoped things would get better and didn't.
When I wonder what's wrong at Minnesota, I keep going back to this same idea. Joel strikes me as a guy that's tough to work for in more ways than one. In another post I recalled how miserable Monson was and how it might have affected his job performance as well as how miserable Tubby seems.