>>> In hitting or golf there is generally discussion of wrist action. I will call it breaking/cocking/uncocking the wrist. If I place both hands on a bat or a golf club, the wrists cannot break individually. If they did the bat or club must bend. The wrists are cocked and uncock by the shorting and lengthing of the arms, generally by bending or straighting the trailing elbow.
Grip pressure makes my forearms tighten and this makes the arms difficult to shorten and lengthen. When I lighten the grip pressure, shortening or lengthening one arm can break both wrists with little effort. Is this the reasoning for light grip pressure for good wrist action? <<<
You make a good point that gripping the bat to tight causes tension in the forearms that reduces bat speed development. However the loss of bat speed is more due to restricting the bat's acceleration from the pendulum effect (CHP) than from restricting the application of torque. Due to the spacing of the hands (and wrist) in the baseball grip, the axis of the bat's rotation is somewhere between the hands and the tighter the grip, the more restriction each wrist offers to the bat's angular acceleration.
Here are a couple posts from the Archives on the difference between the baseball and golf grip and my take on "Wrist Snap."
Torque & Wrist Snap
Golf & Baseball Grip