Pitching / Throwing issue

Supinating meaning thumb turns up? I tell my 9 year old to turn his thumb down and cut the ball in half with his middle finger.

You could always turn him into a pitcher who throws a cutter.

Actually, what I've seen for that is to take a hockey puck or chewing tobacco can and have them try to flip the puck or can overhand without having it wobble.

Another approach is to mark a line around a ball and then after gripping the ball such that the line is between their pointing and middle fingers have them try to throw the ball without making the line wobble.

Thanks...his ball actually does hook a little when he's on the mound. I did color half a ball with a sharpie so that if gripped properly he would throw a 4 seam fastball and the ball should show half white / half black when thrown. If he concentrates he seems to be ok...but then he he doesnt follow through on his throws (throwing off his back foot)...creating another problem.

I like the hockey puck idea...I wish I could cut a 1/4 of a ball from each side and just have the middel part...the hockey puck seems like it would be a little skinny. But I'll give that a try.

Sounds like what you are doing is working. Changes like that don't happen overnight. Keep reminding him and he'll get it eventually.