His effort and attitude was one of the better ones, but he needs to continue his development and technical quality on the ball...especially if he's going to play as an 8. His passing intent is fine, but the quality of his passing the actual execution of it, especially anything over 15 yards needs more touch/finesse.
His first touch in the first half into the box was horrendous and worse than Lukaku. We can't ignore that. He had a much better first leg.
Needs to stay in the first team rotation to improve but he can be upgraded pretty easily. If he's the extra midfielder near the box, with Fred or someone as the deepest midfielder, McTominay's final third play has to increase 2 or 3 levels for United to consider him to be a first XI player.
He's young and he's still in a small sample set.