Well A shorter Span Should Get you out of the ball Sooner and Possibly around the Ball more(Depending On how good you are)
And Having A longer Span Would Give you much less ability To get around the side of the ball basically making you more up the back of the ball(More end over end Roll)
Now those are dramatic Cases If you change your span 1/16 or 1/8th Probabaly very little if any change to your PAP.If you change your span and pitches you could Have more affect on your PaP if done pitches are changed when you change your span.
Hope that Helped