I actually keep a dozen underfed alligators in my backyard. I drag them out once a month and tote them to pitching class.
Then I go about furiously digging a large pit and filling it with water. I then proceed to dump said alligators into pit.
Next, I lay out a board across the pit and instruct my pitchers to pitch down the board and avoid falling into the pit as much as possible.
I have a high success rate with this drill, and those that can't do it don't need to be pitchers anyway.
That's what my DD needs to keep her from leaning to the 3B side!