Harbaugh does grind on the players and has for years—going all the way to his coaching days at Stanford. His act wears thin quickly. He wins and is excellent, but he also engenders a large number of people wanting to punch him in the face.
So that’s the theory around the league: Harbaugh’s act is wearing down the locker room, and it’s starting to show this preseason. Who knows if that’s true, but I can tell you that’s being said by a lot of team executives in football.