Thanks Nigel, good point. I was going off an image of a friend wearing a BD jacket and it has bunched weirdly in that place rather than at a sharp corner, probably due to the fit and thickness of the cloth, but you're right, it's too exaggerated on the figure and, looking back at the picture, it's more squished out to the sides than I've managed. I might try to sand it down a bit in the crook of the elbow, I might even resculpt it a touch. That arm was a bit of a pain, a solid hour of pushing putty back and forward and being unhappy with it so maybe taking that bit out and re-doing it is the best way forward.
Thanks again, fresh eyes are always handy.