Apart from not wanting to injure one of our star players, I think it is problematic to team defence to have one of your defenders periodically heading to the ruck. Sure, he can pinch hit in defence (as could Barrass) but I don't think second ruck works for a defender. Defence needs consistency. A froward pinch hitting in the ruck seems to be less disruptive to structures.-Ive mooted the idea before and with all the chatter about McGov being worked out/around why cant he play second ruck??