I think the Cogger selection is Ivan covering all bases from his 4 locked in reserves. Barring early injuries.
We have two middles in Sorrenson and Phillips. Garner can cover edge, and with a rejig covers all the backs. Cogger is the Half and Hooker cover.And a role of spelling Yeo, and playing as a ball playering lock.
That 4 at the moment covers all positions.
Ivan likes to lock in his 4 reserves with about 20-30 left on the clock. At least in 3 games this year he has done that.
That is my thinkimg of why Cogger is being used in the rotations.