My broad issue with him has always been that he can't play at the sort of pace that successful teams need to be able to play at. Hakan gets the ball and moves the ball quickly and efficiently to make himself press resistant. Asslani is usually playing against weaker teams less likely to press him anyway, or against stronger teams later in the game when they are tired and not so dynamic, so he gets the ball, touches it one way, stops, knocks it the other way and invariably spends 5 seconds or so on the ball just to knock the ball a few yards square or back. This allows opponents time to get back in shape.
The last couple of games in which he has started has shown a lot. Against Venezia he definitely tried to play quicker and more physically (another quality he also lacks) and it was an untidy performance that gave away a number of free-kicks as he was out of his comfort zone trying to play at the pace the rest of the team around him does. The Bologna game was even more marked as they pressed and they particularly targeted him forcing him into all sort of errors. He looked really lost.
I'll always maintain that I do have some sympathy for him as I've never thought he was a midfield anchor anyway, but while he is young and can improve technically and tactically, I just don't think he will ever have the pace of thought, the pace of play and the physicality to be able to prosper in a competitive side.