Here's what I was told re:Harbaugh's deal. The Niners held all the cards in this situation and were NOT going to let him go to Oakland which was Harbaugh's preferred choice. Harbaugh wanted out as bad as SF wanted him out so, as they said, the parting was mutual. However, the parting was only mutual on SF's part as long as Oakland wasn't involved. In fact, they preferred him being out of the NFL.
Harbaugh gave Oakland a deadline to make a deal with SF that was never going to be made on SF's part. And Oakland had to tread lightly with any talk with, or of, Harbaugh because of fear of tampering rules. In the end, when there was no chance of Oakland happening, Michigan moved to the forefront and that's where he is. Take it fwiw.
I think it's great for the Cards, especially if SF would hire Shanahan, and great for the Big 10.