Walker at RB this season has a lot of the strengths that Fernandinho would have had in DM had he played there this season.
Not really the most suitable for a Pep team (although Fernandinho is significantly closer than Walker is to being suitable), but has a certain defensive nous and capability that means that when our press and other defenders crumble you can rely on this guy to get you out with conventional defending.
Hopefully Laporte and Mendy being fit and firing as well as Cancelo breathing down his neck get him back up to his levels in the second half of the 18/19 season; quietly very effective.