Overall I think our locks are pretty poor, Simmons is a mainstay because of his line-out ability but offers little outside of that, a reasonably high work rate but no physicality or presence.
Coleman and Arnold have show glimpses of of good potential but neither are hammering down the door to be an immediate starter. Still a work in progress.
Carter, I've been a critic of Carter for the last 2 seasons, I still think he gets selected on form he displayed in 2014, plays similar to Simmons, decent work rate but lacks physicality and goes missing.
Skelton, straight up lacks fitness, Wallabies can't carry a 50min player...
Douglas, he isn't the prodigal son but based on the 2015 RWC form he is the best we have..
Compared to the Boks, England and the All Blacks the Wallabies locks is one of the weakest areas in the team.