Walker also pointed to the need for cohesion from all 11 players on the pitch, rather than putting the blame solely on the backline.
He added: "This is the most frustrating thing as a defender. I don't care about scoring goals, I'm bothered about clean sheets and we're not doing that. You have to go back to the basics and get a clean sheet. If we concede four goals at home we have to score five. It's not just the back four, five or six - it's all 11 players on the pitch."