Although Cooper is still contracted to the Reds for next year, new coach Brad Thorn has made it clear the 70-test Wallaby isn’t part of his plans.
McKellar, who coached Cooper when in charge of Brisbane club Souths, was diplomatic about Thorn’s decision.
“Quade is a good fellow and a very good footballer but Brad has got his reasons for making decisions,” McKellar said on Thursday.
Was it a shock? Yeah it was a shock to everyone that a player like Quade will be moving on.
“But they make their decisions for a reason, we’re not involved in the inner sanctum there.
“But we don’t have any room for Quade in our salary cap.”
Last season’s first-choice Brumbies five-eighth Wharenui Hawera is part of their five-man pre-season leadership group.
It also contains 2017 captain and lock Sam Carter, hooker Josh Mann- Rea, centre Kyle Godwin and backrower Tom Cusack.
McKellar will settle on his permanent group in the new year but wants to avoid the kind of vacuum in that area that happened once before.
“I want to make sure we improve our existing leaders so when they move on that we’ve got guys ready to go,” he said.
“So that we don’t have the same thing probably happened a couple of years ago when we lost a lot of senior players and Christian (Lealiifano) got sick and there was a bit of a gulf in leadership there.”