Looking at this shoulders and muscles for McGregor I cant think of anything else but him using some kind of steroids.
I do hope they will be testing them before the match.
I do hope they will be testing them before the match.
Or he could have focused more on shoulder and biceps/triceps during his training with metal
Or this was achieved due to lots of wrestle training 
Seriously i do not see any transformation in this image, the only difference is that his dick is more visible in the image in the right .
. That is just a groin guard
