If Tiger is really using an arm swing....there is no way he is just a left arm swinger, he generates too much clubhead speed to be just pulling with his left arm....
RR
No matter how 'quiet' Tiger thinks he is keeping his Body, I think we can all agree that there is more than a little Transfer of Momentum going into that Left Arm! Per 2-M-4, the true Left Arm Muscle Power contribution is feeble, even in Left Arm Swings.
This misconception -- that the Left Arm itself is doing a lot of the work -- highlights a great misunderstanding among players -- including TOUR-types and their teachers. The Arm is providing a very important function simply by serving as the Radius of the Stroke and, also, as the Checkrein of the Right Elbow. However, its 'Power' is derived from the Body's Momentum Transfer. And all that is required for Momentum Transfer is that the Body lead. That leading Motion does not have to be vicious: In fact, as I have pointed out in several posts, such Motion can be -- and often is -- counterproductive.
As far as Tiger learning to emphasize his Arms for Power and his Body for Balance, well, I'm happy for him. He is recognizing two of the cornerstones of The Golfing Machine:
The Arms are Zone 2.
Power.
Force.
The Body is Zone 1.
Pivot.
Balance.
These Zones were established by Homer Kelley years before Tiger Woods was born. He defined them. He listed their Components. And he delineated their respective assignments.