Cooper wasn't signed as a LWB. He was forced to fill in there when McFadzean got injured, and he did so well that it became his position under RL. He should be given credit for that. However, even then he wasn't great defensively and it was in League Two. I think we all realise he shouldn't be playing there in a top half League One team.
Hopefully he makes a full recovery and has something to offer in one of the two CAM positions when he's back.