The wrist roll back slappers I've watched had gross problems long before the wrist roll. Generally standing straight up and effecting a push disconnect like the quickhands cement trowel video I occasionally link with an upper body dominated weak hip rotation swing. They have been start from ground zero remake the swing cases ime. Thankfully I don't see it nearly as much anymore. When showing that static push back example be careful you aren't demonstrating a push point/contact point out in front with arms extended but rather a contact point between the feet.