If MacIntyre doesn't show significant progress this fall, then year 4 won't be any better. Last season was nice in some aspects, but nothing really tangible came out of it. If there's a similar showing this fall, then the doldrums will really settle in.
That 4th year could really get the feeling of a lameduck year, and I think RG realizes he can't afford that with the money they've invested.
Are you talking about the money invested in facilities? If so, that's irrelevant to this discussion as that was happening regardless of coaching situation. If anything, the financial motivations should be on the side of keeping MM around to avoid a 3rd buyout in 5 years.