The funny thing is that CBB wasn't known for paying players well in the NFL. Now he's going to be dealing with NIL, where pay isn't required, its just how you improve your talent. Is he going to come in thinking, I can take limited talent (read scholarship only) and win?
He won in NE because he had Brady, who was able to elevate the slightly above average (read cheap) players around him on offence. His defenses were always complex and smart, but I believe one of the reasons Saban retired is because of the transfer portal, you couldn't develop the players into that complex defense and he saw where things were headed.
If that is the case, and Saban didn't think it was sustainable, I don't think Bill is going to have any more success.