In glimpses he looks a real talent. You could make a compilation of all facets of his defensive play, maybe outside of aerially, and he would look so impressive. Quick, strong, aggressive, nice and agile, and he can look very good on the ball as well, just winning it and playing quick passes forward. When he is on and focused he dominates strikers.
He should be much better than he is, but these bizarre mistakes he makes out of nowhere, random spasmodic body movements, moments of switching off completely, he must be so hard to play with and coach. You love his talent but you can't be that erratic in that position.