Sometimes it's easy to forget just how good a football player Shaw is. Everything just comes so naturally to him, and he came on and his positioning, movement and passing were just about perfect. Perhaps pushed out too aggressively one time which allowed the opposition to get in behind, but I tend to think he did the right thing and somebody else should have dropped to cover that spot.
If he can stay fit, I think there's a very strong chance he ends up first choice in that spot rather than Martinez. Unfortunately that's a very big 'if', but playing that role may reduce the amount of injuries he gets a bit. Alternating the two of them so that they both play one game a week might just be the best option going forward.