[Daryl]

Technical reasoning:
If they move at the same RPM and the clubshaft is twice as long as the left arm, the clubhead speed would be 3 times as fast as the hands speed - all due to increased swing radius. With a hand speed of 15 MPH that gives you a club head speed of 45 MPH. A shaft that is twice as long as your arm is probably an illegal driver so the 45 MPH figure can safely be regarded as a theoretical maximum.Now, if the club head speed really is 100 MPH, you have at least 55 MPH that aren't yet accounted for. You need higher RPM to explain it.

A more golf like explanation:
You don't have to be a mechanical engineer to get this. Remember that between 9 and 3 (as in a 9-3 drill), the left arm goes from parallel to parallel (to the plane line) while the club shaft goes from vertical to vertical. Parallel to parallel means that the left arm rotates 180 degrees. Vertical to vertical means that the club shaft rotates 360 degrees. So in average for the 9-3 motion, the shaft has twice as high RPM as the left arm from 9-3. If you account for a late release here, we are certainly talking about a much higher RPM difference through impact.

Only if you zero accumulator #2 and #3 (or freeze them) will you get the same RPM for arm and club shaft. I guess some does that with the putter but that would be the only shot where this is possible.

Between 9 and 3 (as in a 9-3 drill), the Left Arm goes from parallel to parallel (to the plane line) while the Clubshaft goes from vertical to vertical. Parallel to parallel means that the Left Wrist traveled "X" distance. Vertical to vertical means that the Clubhead traveled a greater distance. So for the 9-3 interval, the Clubhead travels farther than the left wrist.

But because the Flat Left Wrist and Clubface remained aligned (Left Arm Wedge) during the 9-3 interval, they have the same Rhythm - RPM.