Roger, Wait a minute. You want to supinate rather than pronate.

I prefer the ol' #1. A two seamer w/ movement.
I also like the 4 seamer with lot's of ....gidee up.

However, I think it's more 'natural' for
the arm / forearm to supinate immediately following release rather than your approach
to forced pronation. I can see from your
explanation something that is commonly
referred to in baseball as, pronator sydrome.

Pronator syndrome refers to a disturbance in function of the median nerve due to some mechanical abnormality at the level of the forearm. This is most often related to the path normally taken by the nerve through the middle of the pronator teres muscle, although other areas may be the site of the difficulty. Pronator syndrome may resemble carpal tunnel syndrome, but is much less common than carpal tunnel syndrome. Unfortunately, there is no reliable nerve test to confirm the diagnosis except in cases having nerve damage. Pronator syndrome is usually treated conservatively, with surgery to release pressure on the nerve an option for severe cases. Pronator syndrome may be an explanation for persistent or recurrent symptoms following surgery for carpal tunnel syndrome, and may be part of a double crush condition. Outcome following surgery is unpredictable, and at least one out of three children have lingering symptoms despite technically satisfactory surgery.

We may want to refer to JT expertise here.

cheers
Bear