He has always looked like he was done for to me after a 30 yard sprint in his time here.
Whilst I don't think he's elite at anything, he's very good at a lot of things. I have always thought, as stupid as it might sound to some, if he was 5'10" he'd be one hell of a player: but he's not and he really does get buffeted around because he's so tiny. Because of that I think he knows he can't take chances on the ball and that makes him cautious in possession. He's too eager to play a pass, any pass, too often, and that means his passing ability--which I think is potentially very good--is far too conservative and not progressive enough.
I think he'll find his game in time at a big club, but I don't think it's only Emery preventing him from shining here.