The ex-coach is almost always the bad guy. But the Belichick tree isn't exactly know as being super friendly. Dolphins knew what they were getting when they hired him
Coaches can be assholes, but they gotta check a box. I don't know Belichick too well, but for a guy like Popavich, he was gruff to the media, but was apparently beloved by his players and would lie down for them. Other guys are really in with the owners...or with the fans or whatever. Sometimes the other coaches and staff love them.
Flores was none of these. The players didn't like him. The owner couldn't get him to cheat the way he wanted so it's not like he was a toady. His staff didn't like or trust him. And the fans didn't like him. He was the worst of all worlds.