[pure imagination] With the way the ball would have to glance indirectly off the bat in the event of a popup, I think that would create a little more spin that a batted ball already would normally have, so the likelyhood of a tough hop is almost certain, unless you're standing on abnormally tall infield grass. Furthermore, if an infielder lets it drop and doesn't have it in firm grasp and ready to throw within about a second and a half or so, that just about negates any advantage you would have had. Granted, the necessity of the infield fly rule means that doing this is indeed possible and has been done or tried on plenty of occasions, but I just can't imagine it would ever be practical, especially in the cases you mention which aren't protected by the IFR. [/pure imagination]