"who is DJ".....
I love it. Who is the arguably #1 player on the ATP tour? Who also has interview/instruction vids of him saying he flicks his wrists on almost every shot.
BorisBecker, I hope you remember the name, says the same thing in his vids.
Vids of both players show they don't flick their wrists at all. The use the wrist as a hinge, they twist their arms with their shoulder muscles, but they don't actively use their forearm muscles to bend their wrists.