It seems easy to imagine the low weight, tall kid throwing harder. That player just needs to get stronger. It's harder to see the big kid throwing harder. What does the muscular kid need to do? He needs to do things that we average parents/trainers don't know or don't understand. He needs to recruit his muscles, torque his body and limbs in ways that we (and likely most high school pitching coaches) don't know how to train I think. Hard to screw up as a coach training a lean and lanky pitcher--just have him gain weight and get stronger--at least that's the common thinking. I'd like to find a coach willing and able to train my less projectable kid.