I think there are several reasons the change up is not used properly by pitchers and coaches. I think many times the parents get caught up in throwing 6 pitches at a young age and the change up is not one of those sexy pitches to mention. I think coaches don’t understand the effectiveness of the change up and rarely use it at the younger ages. They just want to see fastballs and call movement because all the best young pitchers have 6 pitches. So the kids and parents never really put in the time to master the change since the coach never calls it. Then as they get older why work on a 10u pitch when I’m old enough to throw high fastballs that some call a rise. For us we are completely the opposite and my DD going into 14u is one of those boring pitchers that basically has 2 pitches. She has some others we are working on and throw some in games to get them ready as she gets older. But it’s kinda satisfying to watch her shut down some of the top teams in the nation with just 2 boring pitches. Although I must say she has very elite speed so that helps and makes change of speed much more dramatic.