They also increase chance of injury, to not say that they don't is ignorant. IMO an ounce or two maybe, but any heavier then that and you could be headed down the road to elbow, shoulder, or wrist injuries. I would also think that to use weighted balls, with a pitcher with flawed mech. just increase that risk. Now add in the tought by the parent or pitcher themselves that more weight means more benifit and they add more weight then they can handle. I just think it is a slippery slope to go down. How about some core work on the body or working on the mechanics. I'm just saying this because it is not a lot of fun to have your tendons pinned and screwed back on to the bone or have the bone drilled to loop the tendons back on. I've had 2 surgeries on my elbow and it has never been the same since. Just becareful on the weighted ball ideaWeighted balls do have their place and do increase velocity. To say they don't is ignorant.
Weighted balls should be used sparingly and only in warm up. No movement pitches. Sme with lighter balls.