It's a good tool. Like anything else its not a magic bullet. It's seemed to cut out inefficient movements and helps with direction. Stride has lengthened which is an indication of improved lower body involvement. Would recomend if your son is committed and willing to put the work into it required to see results. Won't do much if he only puts on once a week to throw a bullpen. If you email Lantz he'll answer questions, very responsive.