Agreed. But I think he could make a quite decent Premier League wing back and he should learn a lot from Isla, who is an expert wing back.
Onuoha as a first choice against every team we suppose to play attacking and a free flowing football. Dunne as a first choice if and when we need to play "park the bus-tactic".....
Sorry I was including wing backs in "midfield", but to be more precise then I don't think he'll make a decent PL player in any position more advanced than in a back 3 or 4. From what I have read Isla can play left and right wing back, and won't be surprised if he plays LWB instead of Traore when he's fit and eligible. Phillips, SWP and Hoillet are all possible alternatives to Simpson at RWB.
