Nameless I hope we never see him play, and that's not being antiZat.
Even if Pearce was injured (and Clark has said he's fine) Cooper and Hector are more than capable of playing out the rest of the season. Both comfortably good enough at this level and would benefit from a run in the side. They could be an excellent long term pairing for us.
Perhaps long term, but I don't think Cooper is good enough for us yet. Along with Patrick Roberts, he has the worst successful-tackles-per-match ratio of any defender or midfielder in the league (according to WhoScored). I'd be very wary of playing him against a side with a tricky forward.
Still, at this stage of the season I think we should be giving players a try. I'd quite like to see Dickie or Hyam given a try, but Cooper's got plenty of potential and I guess he's not going to improve unless we play him.