Rick, I might suggest you take a look at this clip frame by frame:
Hillhouse Riseball
Bill is obviously a high level pitcher. However, the fallacy that a pitcher can keep his/her thumb pointed at third thru the release as you suggest above, just isn't biomechanically possible while generating velocity.
The Glenhumeral joint just won't allow it when using proper mechanics.
If you notice, Bills arm/wrist internally rotate hard the instant of release, and his fingers actually points toward first for a moment, just as I've described earlier in this thread.
He then re-routes his hand to a palm up position during the follow thru, long after the ball is gone.........
What Bill IS doing, is attemping to minimize side spin by limiting the amount of internal rotation to the best of his ability. As all high level pitchers do.
That was my point. We TRY. But the fact is WE don't.........
The simple act of "trying" relates to a more "pure" spin......
When we throw a riseball, we acheive slightly more supination (forearm/palm to the sky) on the down swing, keeping our wrist inside the ball longer. The index (control) finger is attempting to cut under and up the front of the ball which delays the internal rotation at the fingers for a moment in time and allows release timing to flow directly at the target with backspin.
Some actually internally rotate and pronate (to palm down) the hand and fingers forward "across the bottom" of the ball, creating backspin. These pitchers usually show a "short" follow thru on the rise.
I can show you a "familiar example"........
There are many ways to achieve a riseball.
But believe me, internal rotation occurs thru release, and the thumb must rotate with the hand/forearm/upper arm/shoulder.......
Bill's clips are telling the real story.........
Unless you are taught improperly to pronate the arm/hand (palm down) by 9:00, getting the hand on top of the ball and pulling straight down and up through release............Which are completly the WRONG mechanics for fastpitch anything.......
The bottom line is, IF you are properly supinated in the down swing, the arm MUST/WILL internally rotate thru release to prevent unjury to the glenhumeral joint.
The rotational torque created by the internal rotation of the shoulder/upper-lower arm/wrist and fingers with this "natual move" is the essence of velocity in faspitch.......The key is KNOWING WHEN TO LET GO to take advantage of maximum acceleration of this rotational torque......
But that's a whole nother thread.........
Can't wait to see Sarah's DVD..........Congrats........
I guess I am splitting hairs here, but when viewed at 600 FPS Sarah's thumb is pointing toward third when the thumb begins its release-------it really depends on where in the release phase you view the thumb. Immediately after the thumb lifts off the internal rotation is very evident and your description is very accurate.
When viewing high speed video it is amazing to see how much happens from the time the thumb first lifts off the ball until the ball finally departs the index finger.