Of the top of my head, Carrick is one.
And there's plenty coming from abroad too. Granted it shouldn't happen to Fellaini but each player is different, maybe he needs more time.
The reason I think he could improve is, and it just my opinion, he was better in every single facet of his game at Everton. Some people here love to rewrite history and say he was always a shit player but at Everton he actually shower technical ability too.
He has his limitations - he isn't intelligent enough to be a holding player. Not is he technical enough to be our 10. But if we play a diamond, there is scope for someone like him as a backup to the two in the middle . I don't think he will make first teamer unless he significantly improves.
The big thing also is at Everton, he was a greyhound. He wouldn't give a player a minutes peace. At United, he has been so timid. If he can find that aggression back he could be useful in a Khedira type role against the big teams.
As I said this is purely my opinion and speculation. He could well turn out to be shit and if we sold him in january I wouldn't particularly care but the notion of writing players off so quickly as if we all own mystic balls is just wrong. Goes for any player.