As someone who grew up in Ann Arbor and spent some years at U of M (i also attended UM) and was in middle and high school during Harbaugh’s time at U of M, I’ll throw in my 2 cents.
Harbaugh the person is disliked in Ann Arbor, despite being an alumni and former star. He’s a jerk and always has been. Harbaugh the coach was thought to be so good that his personality could be overlooked. But when you lose and you are a jerk, people are ready to show you the door.
And he grates on people. As a result, his hard charging ways are embraced early on. But over time, his players, and the admin have come to hate him. And his high salary makes him easy not to extend or re-sign. He’s gone at the end of the year short of beating OSU which has 0% chance of occuring.
U of M’s issue is that whereas the school will spend, and has, lots of money, it holds itself to a higher standard than the schools with which it wants to compete against; OSU for example. Last year in October in an article, Justin Fields mentioned how he had yet to step foot on campus for a class. All his classes were online to save him from having to associate with regular students. U of Michigan would never allow any player not to be of the student body. When I was there, the Fab 5 were in school, Desmond Howard won the Heisman and the Hockey team was winning championships. And all those guys were on campus and visibly attending classes (we all skipped some classes but they were present). U of Michigan and U of Miami both want to be everything in sports and academics. And its the desire to be great in academics that sometimes runs up against the Bamas, Clemsons, OSU, Oklahoma and LSU’s of the college world.
Can you convince a young man who only wants to reach the NFL that its worth his time to attend biology and history classes when your competitor is telling him that as long as he plays well the tutors will take care of his assignments? And of course there are good athletes who also care about academics, but there are not a lot of Justin Fields or Joe Burrows. I’m not making U of M or UM to be holier than the rest, but they have chosen to play by a different set of self imposed rules which make it harder (not impossible) to succeed at the highest level.