Welcome CV! I had the same question and the final phase of the release to post release just didn't seem right for my DD. I always could tell if she was truly using I/R or not by the speed of her ball. Sometimes it was real fast (comparatively speaking of course) and sometimes it wasn't. She would brush, palm to sky, etc. etc. but I knew there was something just not right (some of the time). Anyway, I came across 2 things that helped it sink in with me and with my DD.First off, hello to all and what a great site! I find myself having to learn about pitching. I come from a small rural area and, like a general practicioner doctor, I need to know a lot about everything. I have read most of the threads on IR and will continue reading. I'm pretty sure I understand the difference between HE (back of hand facing target after 12) and IR (palm up after 12). Where I am having the most trouble is post snap. I keep reading that the hand should act likes it's closing a door, ie a horizontal motion. but the snap is a vertical motion. so how does this work? does the natural motion of closing the hips act as a transition movement? (Just so you know, I am working with 10s and 12s but now the older girls want help, too.)
1. If you haven't seen it already check out Pauly's Whip Flip Drill with an emphasis on the last 20 seconds or so. Watch it several times.
2. The other is a quote from Sluggers and probably the biggest "light bulb" moment for us on this topic. Once I mentioned the "THUMB" and how it should look (which is the same in the whip flip (or at least my interpretation) my DD ran with it and hasn't looked back. Below is the quote and it is in the Basic arm-body synchronization sticky post #22.
Sluggers quote "Good IR involves rotation of the radius over the ulna. The easiest way to track the rotation is to look at the thumb. The thumb has to be on the third base side of the ball at release. For good IR, the thumb should be on the 1st base side of the ball when follow through completes. (Yes, I know that no forces are exerted on the ball after release. The follow through indicates whether the forearm was rotating at release.)"
For me, it was these 2 things that finally made it sink in. But I am a very slow learner.....
I hope it helps!