[bambam]

However I have read a few hitters say that in hitting pp #3 is more active.

I wonder if they were referring to the downstroke? Since hitters load behind the shaft and have a simultaneous release (uncocking and rolling at the same time), they feel the weight of the clubhead lag in pp#3 sooner than a swinger who's pp#3 is under the shaft and using a sequenced release (uncocking first, then rolling). The swinger's pp#3 in that example would be in more of a supportive role until the hands swivel into impact, when the full force of the clubhead lag pressure is against it.