Boss first half, worse second: tiredness and/or the the little injury. And maybe because he was on the other side on the pitch, not the usual spot where he settled already with Coleman, now he had to link with Oviedo which seemed a little uncomfortable for both of them. I think if RM wants him to heal completely than he have to play Barry and McCarthy against Chelsea and rest Mo. It was a miracle anyway that Barry didn't get his yellow yesterday so he'll probably get it against Chelsea. And the week after that game the games will come rapidly: EL, PL and at end of March the EC qualifiers.
And next season (it won't happen earlier) when Barry gets less playtime him and McCarthy will be absolute bossing the midfield. It was clear yesterday at the second half that Macca has got 10x times more PL games under his belly than Mo but what I've seen was that they'll be absolute BOSS together.