It isn't that he's shit, more a case of we've been shit and haven't been in a position to get him settled via doing his job. Same goes for Klaassen to some extent.
Fellaini comparison is interesting - he'd likely be in the same (Sandro, Klaassen) boat if back then was now. And vice versa. Hopefully things work out for both. Definitely good, potentially great players in there.