His ability to play against higher level players. There have been no players he hasn't been able to defend against.
Maguire requires 2 DMs to protect him against stronger attackers.
Shaw's consistency is a little better.
He's just a higher...
Ok I know this won't be a popular opinion, but don't attack me. I think Shaw has been very good and he takes a lot of pressure off of Maguire and the defence in general.
This is how I see him. Far from our biggest concerns but if we want to be world class then at some point we would need to upgrade.
But tbh the bigger concern right now would be if he got injured.