Faster speeds with "windmill"motion

Hi everyone! I am a former Strength and Conditioning Coach for Northwestern University in The Big Ten. My recently-turned 10 year-old son Brock plays AA ball in suburban Memphis, TN. His fastball radar speed had been sitting at 51 mph for about a month so we decided to try an experiment. From the windup stance once the ball is at full extension behind the body we bring the arm up over head while keeping the elbow approximately 90% straight…like a windmill. We lean far forward after a long step and release late. We are finding that this quickly adds 3-5 mph as compared to a more widely-used motion…one where when the arm comes up from full extension behind the body the upper arm is more perpendicular to the body with the elbow higher than the shoulder. I am curious if any of you have found this to be the case as well? Bob

I don’t follow your description. Can you post some video?

Welcome! I’m with Roger in that video would be most helpful in offering you advice.