The location of #3pp for a swinger with the feel of it being under the shaft is due to the position of the hands at the top of a longer backswing and the turn of the hands. All hand and wrist actions are a loading procedure. Swingers using 10-18-A Standard, turn and cock on the backstroke and roll and uncock on the downstroke. This loading procedure will give the feel of #3pp relocating but it is always behind the shaft and will be there-behind- at impact.
The right forearm take away motion should be the same for both strokes. The shorter shoulder level Hitter's top position using 10-18-C keeps #3pp aligned and the Swinger's longer top position using 10-18-A requires an unroll and swivel into a impact. The take away motion is the same, the loading procedure of the hands are different.