So if he doesn't like a system were you share the ball, why would he be happy here?
This is an fair point. That said, I think such concerns could be alleviated since he's friends with Crowder (college teammates) and part of the discontent is just that Butler liked Thibs. So the person replacing Thibs was always going to have to prove himself. Stevens wouldn't start from such a disadvantage, and he enjoys a great reputation around the league, so buy-in might be easier.