My eleven yr old pitcher has been throwing exclusively 2 seam and 4 seam fast balls. He throws a measured 62 mph. We have started working on a change up. We didn't get very much difference in velocity on the normal change up grips, so a "dead leg" change up was shown by an instuctor where the back leg stays on the rubber and does not follow through. Otherwise it is very similar to the circle change. The change in velocity was dramatic - 44mph. My question is will this delivery put undue stress on his arm or shoulder? We watch his mechanics closely and his pitch counts. Haven't had any issues. Any thoughts would be much appreciated. Thanks.