I see it as a whole team issue rather than something which is solved primarily with the centre backs (They do some dumb stuff from time to time though).
Luton's second goal on Saturday was a simple infield ball finding their midfield in acres of space, not sure where Sheaf or Eccles were but it was over before I could spot them. There's been other moments which I can't evidence right now whereby there's a space in front of the backline which has lead to goals.
My point is that any defence in world football is going to concede goals if you allow it to be tested enough. This can be remedied by either keeping the ball a lot better than we do (which is another reason why I moan about decisions like putting Kitching at LWB) or by tightening the space between the lines.