I am happy to give Stef time, but I can't see him making it as a ruckman.
It is a few things...his inability to time his leap (goes far too early), his want to avoid body contact in the ruck (could explain why he jumps so early) and as mentioned, no real purpose or direction when he does get first hands on the pill.
In my opinion, throw Gawn in the deep end. We need a natural ruckman otherwise we will continue to be slaughtered in the clearances like we were yesterday. Surely a > 2m beanpole will provide a better option in the middle.