But where are you getting this "McCarthy is not fully fit" from? The reinjury? The same injury that hadn't shown up in any scans/assessments prior to the game? That McCarthy had seemingly recovered from?
He was short of match fitness, yes, but he wouldn't have played hadn't he been passed fit, an examination of which includes asking the player himself.
Sure it's a reinjury, but that could happen to anyone. He was rusty and the only remedy for that is him being on the pitch and building the match sharpness.
As for Cleverley, he offers a vibrancy and goal scoring threat that neither Gibson, Besic nor Osman offer. It was another risk which partly paid off (assist to Rom) but also saw the realisation of the worry RM obviously had... 2 games, 2 days = injury.
Would you seriously have brought on Gibson, Besic or Osman at that point rather than Cleverly? Seriously?