Walker understands the versatility Pep expects from full back. He can play conventional full back, attacking full back, and inverted full back and he is quick enough to defend when our high press breaks down. Mendy and Zinch both struggle to fit the full package for different reasons. Jury's still out on Cancelo who possibly can but maybe not on the left side. Ake, being mostly left footed fits the bill hopefully. I suspect that's where Pep wants him to play but it all depends (imo) on having a top class CB to partner Laporte.