I don't separate TTB and 'snapping the barrel rearward' as you put it as different things. I don't have an agenda, just concepts that resonate with what I feel myself and what works when I teach. I feel the hands slotting the elbow and the start of rotation moving them forward in space (while stretch and load keep them near the rear shoulder. Actively work the handle and the barrel must turn rearward in order to work behind the ball, for hips to beat hands and max separation and stretch to naturally occur. Those are concepts that would seem to be fairly universal. I don't believe every conversation has to be a vs b, you end up only having a vs b conversations then. Take that away and I don't imagine we'd be far apart in how the barrel works? Maybe? Maybe not?FP26
It's excellent for TTB, not so much for just snapping the barrel rearward. The swing happens more like Mankin describes.
Mankin talks about how the top hand circles around. Hand rotational point (my view) and changing the direction of the knob (my view). Sets up the oar lock effect.