I've never quite bought the 'Koren must be used in the middle' argment, but this signing can only mean we have another option on the wing and it lets us use Koren elsewhere if he really wanted to. We haven't had two wingers available other than Koren since NP came, so he's never really had the option to use him in the middle. I maintain that when he has played in the middle he's been poor, but he could turn that around with this signing.
Koren is an attacking central midfielder, ask any West Brom fan and they'll tell you this. His best games for them were playing in that position he left because he kept getting put on the wing, now circumstances have seen him used for the majority of games on the wing for us. He's just got on with it, as at a guess, he knows NP is building his own squad and we didn't have any real wingers. Now we have the players to put out on the wing (Brady/Pusic/Stewart/Dudgeon) Koren can be used in the middle or behind Fryatt.
But surely the most important thing is his performances for us? He has done some very good things from the wing, and had some poor games in the middle He had once game in the middle at the end of last season (Palace?) and did well but apart from that he was too anonymous when playing there. I won't complain if NP does play him there at some point, but it's not something I'm dying to see imminently.