While the team put together might very well be good the AI has a habit of continuously and completely botching it up. I've seen the AI have one of the best teams in the SHL and still finish dead last.
Edit: As for newer managers taking them over when I have seen new managers take over such teams they typically struggle and botch it up themselves. That said there is a simple solution. Raising the game limits for switching to a GHL or SHL team.