PC used that red thing on DD for two sessions and I made one from a shoe box. - removed bottom and one end, used duct tape to reinforce all around. After a couple of practices- we never needed it again.
Yes, the block that keeps the pitcher's foot straight should not be used. The best drill for push off is the stork drill, where the pitcher starts on one foot. She can put it at a natural angle to start. Not sure why there needs to be an repositioning of the push off foot, whether a slide, a pick up of the toe, or a rocker back and forth. Sprinters just go forward.
Yes, the block that keeps the pitcher's foot straight should not be used.
Sprinters just go forward.
There is one big difference that no one is mentioning when discussing the sprinters start. Sprinters are attempting to keep their shoulders square to the finish line. Pitchers on the other hand are trying to get OPEN when they push off and stride. This is the reason most pitchers turn their pivot foot slightly out to allow the hips (and shoulders) to get open during the stride.
We don't like the rocking back and the forward (or the accompanying glove swing back forward but that is disappearing more quickly). Just want to go forward like sprinters. So push is all on the front foot against the plate or the hole. Sprinters back foot is against a block, while pitcher's not. Running track the back foot was more like a stabilizer, and I ended up doing mostly long jump which is really the front foot pushing off, so long ago can't remember.
I don't like that red torture thing because like some have said, some pitchers/sprinters have an outward angle to the foot naturally. Forcing it straight is a waste of time.
Wide receivers also sprint, and they push with both. Sprinters push with both during relays (no blocks). Pushing with only one foot is only using part of the available power. Long jump isn't sprinting, doesn't apply here.
As for the device, it sure looks to me like there's enough room for the foot to turn/move some. The issue for my DD is she is turning her foot 90° prior to the push/drive. I will have her try the one foot/stork thing, that will save me from having to build the contraption, thanks for the link to the video.