While I'm much more of a listener (reader) than I am a poster, I thought I would share our personal experience regarding stride length since our kids are similar in age but very different in size. My son has what some consider a long stride when he pitches and is certainly lower half dominant when throwing naturally, but what I can tell you is that the day after a pitching performance his elbow may have slight tightness which is pretty much gone after icing but his legs are what is really sore after throwing a 90 pitch game. I will post a pic I took from a game at the end of this summer season. Distance from the rubber to plant foot seems good to me, but I'm just a dad so I cannot really speak to whether his stride is or is not a good distance, but I thought I would share for some perspective.
Son has worked on stride length in addition to control for the past 2 years using yoga, flexibility and core strength training. His results have been noticeable and I've been pleased to see an increase in velo but not an increase in arm soreness. While there may be a lot of contributors to that, I'm a big believer in stride length based on sons experience.
Anyway, Just thought I would share.
