Walker played a solid game last week too but I see your rationale.I think Walker will come out of the side for Robertson. North only have the one key position sized forward in Ben Brown, who Harris will cover. They have a few 3rd tall types but they can easily be covered by Gardiner, Witherden, Hodge and co. Robertson will provide us a bit more stopping power for their smalls and a bit of run and carry out of defence.