There's a moment in this game that summed him up as a midfielder.
We won the ball in midfield and had the chance for a quick transition in midfield. Antony was running in space that opened up on the right wing. Mctominay had the ball in the centre circle and could've played a pass to Antony into the open channel but he holds the ball and runs with it for a few yards taking about five touches until he's a couple of yards away from Antony then passes it to him. He completely ruined a potential attack because he doesn't have the ability or confidence to play such a simple pass.
Casemiro would have played that with one touch and an attack would have opened from that. Mctominay is about as much of a CM as Wout is a striker.
He has two skills on the ball, running into open space in midfield and striking the ball cleanly, that's it. He can't pass to save his life.