Other than the firing scenario, if I were trying to persuade Prohm to leave on his own (the buyout would be part of it, of course), I would actually point to McDermott at Creighton, after his tough time here. McDermott has actually had fairly good success there, other than maybe two seasons, and I think his winning % is something like .662. Of course it helps when you've got a son who winds up POY in college b.b. His success in the Big Dance has not been that impressive, but he's got them there at least. Not to mention that Creighton is consistently in the top ten in attendance figures.
In other words, I would make the "it's just not a 'fit' here" argument to Prohm. It's a common argument in the professions and in business.