He was bought as a centre midfielder, played there for a bit and was moved outwide because he was our only player with a bit of invention about him, he was our only player who could work a bit of magic and cross a ball.
Our game was all about getting the ball in the box and the only wide options we had available to us where the likes of Kevin Kilbane and Simon Davies, speaks for itself really.
He did well out there so Moyes kept him there, after a few seasons it became clear that is just wasn't working any more. He wasn't seeing enough of the ball and the team itself had no one who could do what you want a centre midfielder to do.
So he was moved into the middle and even when Osman and Anichebe where out injured against Boro Arteta was kept in the middle and Moyes introduced Gosling. Even when Pienaar and Osman where out against Villa he was kept in the middle.
Moyes saw the impact he was having and kept him there, the results we where picking up and the difference in style of play was there for everyone to see, as I said, we have never played controlled, possession football under Moyes until then. I have no doubts that he views him as a centre mid nowadays.
It has nothing to do with him not being able to hack the position, it was just a case of Moyes finally realising that you do need a proper 'footballer' in the middle of the park.