I read these moves differently. Firstly, Marion Hobby is an excellent coach and has been recognized as such for a long time. He left because he wanted to leave, not because he was forced out. Hobby is rumored to have accepted a job in the collegiate ranks where he can teach young players and make more of an impact, and the rumor is that he'll be an OC. Whatever the reason, it's likely a step up and his choice.
Gailey always sounded like this was going to be a one-year commitment, and he was going to re-retire after one year. He's old, and he was comfortable in retirement. But the allure of teaching Tua, having Fitzmagic there as the best possible training-wheels, and helping out a friend who would provide a dynamite defense was just too good to pass up. But, I'm not sure that's what he wants as his full-time life right now. Maybe Gailey was let go, maybe it was his decisions, I don't really know. But, I was not a Gailey fan, and even I must admit he did a good job this year, getting the best out of both QB's, adapting to the revolving door of WR's, RB's and OL's while shuffling QB's and reps. He hid Tua's flaws and minimized Fitzpatrick's mistakes. He enabled our defense and special teams to win games without turning over the ball. He scored TD's and points at an acceptable rate for this patchwork/rebuilding offense.
Chan Gailey was not part of the problem, he was part of the solution. Our offense is not as good as it appeared in 2020 ... and it didn't appear particularly good. We need more talent.