Hinge enough or the club gets behind you
Porzak identifies under-hinging as a big cause of an inside takeaway. If the club should be in line with your hands when it is parallel to the ground but you don't hinge the wrists enough, the club stays too straight back and then veers off underneath your forearms, getting the club behind you. The fix he implies is to hinge enough that the club matches your hands at that parallel position.
Channel: PorzakGolf
Watch official source at 6:47