Take a ball and just throw it overhand. That action is the same action your trail arm does in a golf swing. It is a universal action in sports. Wether you are throwing a ball. Or shooting a basketball. Or throwing a bowling ball. The wrist and hand works the same. If you take that same over hand throw. Then throw side arm then under handed. You start to feel how your hand and arm works on different planes. Put that same action into your golf swing. The other thing is that when you throw a ball there is no tension in your shoulder socket. That should be the same in a golf swing.