Rick Pauly says:
This is extremely helpful to know. So many pitchers and dad's taking the advice of coaches regarding RPM's on the drop being different than the fastball. Since it is primarily an issue of release angle is the successful drop in actuality created because the "roll over" and/or "Peel action" combined with the typical "weight forward" advice simply changes the hip and release point height and angle? Not because of the supposed "extra spin"? This would seem to be the case.
Not to answer for Rick but as an aside, when scouting a pitcher, I like to see a kid who stays back on the drop and can start it pretty high in the zone (see the string description above) and still break it hard. Hard and high enough she can get the called strike if there is no swing and yet make the hitter miss on the same pitch if they do swing. I see too many girls who can only make it break if it finishes at the ankles. I view the weight forward thing as part of that problem for geometry/body position reasons too long to go into. I see a kid with a good drop finishing at the ankles I yawn. Not that I don't like a drop in the dirt when it's appropriate. When she also shows me a nasty bite finishing at the knees I go looking for her academic information.