Yeah he did well. Thought he looked weak when he was 1 on 1 against an opposition player. He looked panicky. His distribution was also erratic but if anything still better than the Rio casual hoofathon, or whatever it is Smalling does. Other than that, was an admirable effort.
The key thing is he looked composed and wasn't afraid to take responsibility on. We've played other young players this season who looked either incapable of or too afraid to try and do anything. He was allways putting himself where the team needed him to be, with or without the ball, which sounds simple but actually takes some balls when making your unexpected debut in front of 75,000 people, for Manchester United.
It wasn't just the header either. There were a few times in the second half where other players were caught out and his positioning bailed us out.
I wouldn't get carried away at all as you can't judge a player on one game, against West Ham, but he certainly didn't do himself any harm.