Howard Kobata has broken fielding and throwing down in a way that nobody else does. My daughter had the good fortune to attend one of his clinics four years ago at Elgin, and it really improved her footwork and understanding of how to catch and throw efficiently. If you have kid that appreciates technique Howard will open your eyes to a different way of thinking about the mechanics and footwork of defense. And if you are a coach, he has some fantastic drills, so pay attention.
The biggest problem is that you will learn so much it kind of reaches a point of overload. And don't be afraid to question his technique or suggest what you think is a better way. He can show you why you are wrong in a simple and clear way and not embarass you either.
Skip the high school and college clinics and listen closely to Howard. If you absorb 1/3rd of what he says and practice it, you will be a better player.