The point is, "needs to improve". That's part of the development and progress of players. As a team, we still need to improve, but we've come a long way. Some of our players are not the finished article, they need to work on aspects of their game.
From tonight's match, Shaw is making some great runs but needs to work on making them count, James needs to work on his decision making when he races forward and McTominay needs to improve defensively (assuming you're right that that the plan is for him to replace Matić, which I think is not a given). AWB needs to improve his delivery into the box, which he's doing. But I think they know this, so does Ole and the coaching staff.
Personally, I'm optimistic about all of them, and there's only two or three players, of those we are seeing regularly on the bench, that I have serious doubts about, and I think most people know who they are.