How will he do this? What sort of level do you see him at? One of the best midfielders in the league, a player that all the big clubs in the league would be delighted to have? He'll probably have a couple of 'standout games' against big teams. He had one less foul than the entire Barca team in his 'amazing performance', 15 over two legs is crazy. He's good at that though, and it obviously attracts attention.
Your comments remind me of the ones about Palacios, who while a worse player, showed similar qualities - a willingness to 'put himself about', plenty of 'drive' and the ability to push a team forward with rampaging runs. Diarra's better than him in each case but there's not a lot more to him than that, IMO. He catches the eye because he makes the easy stuff look difficult - beats two men and then loses all composure, realises he can't pick a forward pass and then retreats and passes it back, when he could've just played the simple pass out to the fullback to advance the play 3 moves earlier, but he's beat two men so he's shown skill and quality.
As a 'box-to-box' midfielder I think he's a very decent player but as a defensive midfielder - which he's been for Madrid and France, and what people seem to see him as now - he's really not up to it at the top level because he lacks the know-how to break up the play without simply fouling players, in my view. I thought he'd shown quality beyond that an earlier age and he'd be able to add a bit more craft and intelligence to his game but it hasn't happened. I dunno, maybe it still will.