Organise the back four would be a start. We're all over the place a lot of the time. A decent central defender is a leader at the back and can sniff out the danger and has good positional sense for himself and others around him.
Telling Grimes to fuck off in to midfield and let him take free kicks on the edge of own box would also help.
Also it's not hard to stand out ( I don't personally see him standing out) when you've got a back four consisting of Tymon, Key and Cabango.
Ashley Williams was head and shoulders above this lad at a similar age, now that's a decent central defender at this level.
We can hardly judge a players potential based on the opinion of opposing fans.