Talking about Tarky here or Edmondson?
Decent centrehalfs and young ones at that are thin on the ground and Edmondson has all the attributes to play at an higher level, most don't mature fully until their mid 20's both physically and mentally and he's steadily improving particularly with Clarke looking after him in games, these young defenders are going to have off games, even the more experienced ones like Lovren and Jones don't get everything right so mistakes will happen it's how they react and learn that's important, certainly wouldn't be giving him away for 200k in the current climate.