Practice
Rise and drop ball drills
The all in one ball for rise and drop training, and the drills that use that fact. Contrast teaches faster than volume.
Chapter 01
Close-range spin work
Start at ten or twelve feet from a wall, at roughly half effort, watching the first few feet of flight rather than the target. At that range you are not testing a pitch, you are testing a release, and a fault in the grip or the hand shows up immediately.
Four or five minutes of wrist flips at arm's length before that, with no stride and no arm circle at all, asks the fingers to do the whole job and nothing else. It is the least game-like drill on this page and the one that changes the most.

A plywood crate of EZ-Riseballs standing at the edge of a practice field
The alternating block
Work in blocks of five. Five rise, five drop, then five where somebody calls which one as the arm starts moving.
The called block is the one that matters. A pitch a pitcher can only throw when she had time to set up for it is not a pitch she can use in a game, and the only way to find that out is to remove the preparation.
The contrast is also the teaching. Putting the two releases side by side makes the difference between hand-under and hand-over physically obvious in a way that a hundred repetitions of either one never does.
Chapter 03
Stopping before the fatigue
Spin work is finger and wrist work, and those tire quietly, well before the shoulder feels anything. The first sign is a release that gets slightly earlier, which is precisely the fault most of this practice exists to remove.
So cap the session at about twenty minutes and stop while the mechanics are still good, even when it is going well. A tired drop ball teaches the wrist to open early. That is worse than not practising.
A session that fits in twenty minutes
Four minutes of grip and wrist flips at arm's length. Six minutes at ten to twelve feet at half effort, watching the spin. Six minutes at a short stride with a full release, still close to the wall. Four minutes alternating rise and drop, five of each.
Three sessions of that in a week will beat one long one, and twenty minutes is easier to protect than an hour.
EZ-Riseball, US Patent 9,750,986. Call (334) 531-4739.