Ken De Beasto,
A lot of how the shape is created is about the timing of the release. " Hitting up" on the ball simply means that you have learned a "late" release timing, and are imparting the revolutions to the ball AFTER it has reached the bottom of the swing and has started back up.
Ever played any slow pitch softball? Imagine the difference in the pitchers release it would take to go from a high arcing pitch, to literally rolling the ball across the plate. In the high arcing pitch, he would stay with the ball longer, and release it on the upswing, and in the rolling pitch, he would release it sooner, before he got into the upswing.
Back in the day, hitting up on the ball was not such a no-no. Balls weren't nearly as strong, and weren't going to greatly magnify little release inconsistencies the way reactive resin balls can. Back then missing it just a bit, or grabbing a handful, was the difference in a light swisher and a solid flush strike. Now days, it can be the difference between a washout and a runaway Brooklyn shot.
Throwing my old Black Hammer, you could leave a 5-7 or an 8-10 at anytime if you didn't "get all of it" at the bottom of the swing. That is one of the reasons it is hard for us "old school" guys to adjust to the modern release. Everything about it feels "weak and wrong" because that is the way we used to throw "bad" shots and leave unmakeable spares that ruined good games. What is taught today as "good" and acceptable ( such as forward tilt or dropping your shoulder) was drilled into us as "bad" and un-acceptable, because it created "weak" shots back then. With those older balls, you needed all the leverage you could get.