I've no doubt that Moore and Atkinson are gonna go on to be a great CB pairing for us, but I'm not sure they're ready to go straight in as our first choice pairing right from the start, it's a really important position, where mistakes have to be kept to a minimum, and we need an experienced head alongside one of them, so they can gain experience themselves whilst learning from an experienced partner, whilst also being guided through any rough patches.
At the moment, if Mous got injured, we'd only have Moore, Atkinson and Jones as our senior CB, and they have VERY little experience between them, and I feel a 4th experienced CB is a must.
But you have to tie in the senior places available in the squad. It opens up if Hanson is sold/loaned but we don't have room currently for an experienced CB, left midfielder and striker. Somebody also said about left back cover. So it depends on if any of the last 3 are u21 or Hanson goes out.