A lot of people speak of forearm rotation. I like to perceive it (and tell people when I’m working with them)….that it’s upper arm rotation. Sounds like semantics, but it isn’t. If the upper arm rotates, so must the forearm. The opposite is not the case.
You can fan the club behind you off the ball rotating your left forearm…not so much rotating the left upper arm.
Rotating the upper arms has a general affect of connecting the arms to the turn. Rotating the forearms has a general affect of disconnecting the arms from the turn.
As a side note, Diane Lickliter asked me to post this putter that Scotty Cameron donated to raise money for charity. Below are the pictures and this is a putter only tour players can get.
The current bid is $2500 and here is the email to bid.