Here's the thing with The Harbrau™, the guy can coach. His track record shows that. However, his personality gives him a limited window at any particular stop. His manic, bat-shit crazy way of conducting himself inevitably grates on those around him, and at a point, you begin to see diminishing returns...see SF last season. There's a lot of Niners fans still smarting about him being dismissed, but not me. The guy had an incredible first three years, but by year 4, the players, his bosses, and some of his coaching staff were burnt out and essentially mailed in the 2014 season. I have little doubt that slide would have continued in 2015.
Now, scum fan will say, "but with college, you're turning rosters over every 3-4 years." Yes, that's true; however, the coaching staff around him, and the university administration will grow weary of this madman in due time. And if he's not a smashing success on the field in pretty short order, the patience will grow very thin. Not to mention, a man with the ego the size of The Harbrau™ is most assuredly still stinging from the fact that his little bro has a Super Bowl ring and he doesn't. If he has some success at scUM, the NFL will come calling in a few years, and just like he was unable to play nice with the front office in SF, he'll see those same issues with the administration at scUM as a reason to jump back to the NFL.
I said when they hired him-- he's a Bill Parcells type coach. An absolutely unbearable asshole that, while successful on the field, cannot stay in one location more than a couple of years because his personality simply won't allow it.