I will freely admit that I am no a mechanics coach. That being said, I've been approached many times to "help" out someone who is having issues with spotting weakness(a), in one form or another, with managing their pitching career at various stages in their careers. I've found that age, physical fitness, physical makeup and physiques, maturity issues (yes, even at 40+), all have influences. Fortunately, I've seen all kinds of "I do things my way," that has been the result of self taught stuff, very good coaching for a point in time that had the player receptive to said coaching, and the willingness to listen and identify what they need as appose to what they want.
It's that last item...identify what they need as appose to what they want, that has me wondering about all the training apparatus on the market, particularly focused and marketed to the players 18 and below.
I'm deliberately taking the long way around to address this device, and I have no problems with it. However my experience and observations tell me that someone has to actually know the compromises with their body - thus the shortcomings that require addressing, the surfaces that they'll be working off of to actually benefit from any device... which is a subject all in it itself, and the age that dictates the point in time that the body will actually benefit beyond the device's introduction.
So, there comes a time when this game is truly a game, nothing more. But when it becomes a competitive way of life dictated by serious observations of what's what to work with and why - how- when - and where, devices like the one asked about are nothing more that gadgets .. gadgets that try to bring across a single point of instruction (coach) that can not be brought across any other way. In this way, a benefit is obtained.
I would like to pass on something that I've witnessed over and over again. Regardless how hard and how long a pitcher trains and practices this and that, when under pressure, the human mind will fall back on what it feels most comfortable with ... like a safety zone sort a speak. this comfort zone is a survival reflex that we all have embedded in DNA and it is stronger than any other instinct that we have.
Recognizing this zone in every pitcher that I had, was the first order of business - then and only then could any serious approach be made to either accept or alter a man's technique(s).
(a little overboard on this one, I know.)