If you Cock the Left Wrist with the Left Forearm Muscles, then the Right Wrist will also Cock.
But, if you allow the Right Elbow and Forearm to Cock the Left Wrist, then the Right Wrist will remain Level.
The Center of the Radius of the Left Wrist Cocking Motion is the Right Elbow and Right Shoulder. They travel a smaller Radius than the Left Arm and thus Cock the Left Wrist as the Club is Raised to the Top of the Swing.