And remember the immortal words of Terry Francona (and probably others), coaches get too much credit when teams win and too much blame when they lose. I think this is going to apply here. It is going to be more about how the players actually play than how the players are coached.
This season will be the opposite, I think there's a significant enough portion of the fan base that will leave the season with one of two conclusions:
If the Celtics win a title: "It was all the players, Joe lucked into a great situation. Let's be real, the team went to the Finals last year, added Brogdon without losing anybody, and guys like Tatum/Brown/White/both Williams/Hauser/Pritchard all improved via natural progression. It had nothing to do with coaching." Bonus points if a major player on an opponent gets injured along the way.
If the Celtics don't win a title, regardless of the round they go out: "It was all because of Joe's coaching. He wasn't qualified and just got thrust into the role after the Udoka situation because Hardy already left. How do you take an improved Finals team and not win it all? Really though, I blame management, every other team would have just swept the Udoka situation under the rug and kept him as coach."