Hidraw

With the traditional golf posture, forget about the ball and with left arm only swing, the most powerful swing is when the left arm the hands and the club moving in the plane at the shoulder level like a helicopter rotor, yes? This is where the left side generates the flailing/whipping action from the ground up. But of course, with the left shoulder being so high, the most powerful swing with the left side only would be too high and miss the ball. Tilting the spline helps somewhat. And extending the right arm to lower the hands can certainly help. The spline tilting is fundamental for the flailing/whipping action of the left side. Extending the right arm provides a one-way control about the height of the club head (Bradley also advocates this one-way control). This is analogous to applying a grinder to a surface. Moreover, with the club plane shallower than the hand plane, there is a passive torque to turn the left hand from pronation to supination closing the club face naturally.