Pogue Mahone
Closet Gooner.
You said it yourself Carrick is 32 therefore not in his prime anymore when Fellaini is 27 and logically supposed to show us his best self. Being lenient for a player who isn't in his prime seems logic to me.
You could swap "isn't in his prime" for "is in his first season at his new club" or "is struggling with injuries" or "playing as part of a team having a season from hell" (or all three!) and you'd be talking about Fellaini last season too.
It was a weird season in that way. You had, at most, two United players who actually played consistently well but excuses made for almost every one one of the others apart from the one player who had all their excuses plus the fact he was trying to settle into a new team/club. He basically became a lightening rod for all the anger/discontent about everything else that was going wrong under Moyes (he had the right build for it, to be fair)