It usually burns hot for a couple of seasons and then, once his team gets success, they lose that fire and he doesn't have other ways of motivation. I think what happened at United isn't all his fault as United has been struggling to replace SAF since he retired and their upper management is weak. He won the PL with Chelsea his last go round and his first go round with Chelsea was brilliant. Tottenham has always seemed destined to fail with him in charge since, after he left Inter, he seems only used to working with elite players and he isn't keen on development.