Tribe - height does in fact compensate for a lack of tools! How hard does you 6'5" son throw? Whatever it is I bet it would be a lot less if he were 5'7". Its simple physics. The longer the distance from the middle of your body to the end of your fingers the easier it is to generate velocity. So that smaller kid has to work much much harder to make his core move incredibly fast in order to generate the same velocity your son could with minimal effort. Fact of life and physics folks. And I bet your being modest. I bet your son is at least in the 80's. College coaches will believe they can get him to the 90 range and your son will land somewhere.