"First, is there absolute evidence that the underhand pitching motion is causing unjury in enough frequency to justify any change"
Seriously? Look up a few posts further back in this thread to the ones I listed right here in "Central Ohio" The one girls arm just snapped pitching and one of the best pitchers to ever come through Central Ohio had Tommy John Surgery in Sophomore year?? and cut a career that she would have been amazing. Not only a great pitcher, but great Kid! These are just arm issues, there are knees backs and others....
I know someone who is a well known youth sports DR. with Children's and will ask him how many he has seen over the last ten years....
I didn't say that no one ever hurt their arm throwing underhand. If a girl snapped her arm throwing a pitch, fine attribute it to a pitching injury. You have no way of knowing if the pitcher who had the surgery injured her arm pitching or throwing overhand.
My DD out of the blue said her shoulder hurt and was out of commission for a month. Two orthopedic surgeons and a sports physical therapist all told me that it is very unlikely she hurt her arm pitching, but much more likey throwing overhand. They said they rarely, if ever see injury from the underhand motion.
Strengthening ALL the shoulder muscles, not just the ones we use to throw, and stretching properly will eliminate 80% of shoulder issues, but very few pitchers actually follow a strict strengthening and stretching routine. My DD was given stretches and a strengthening routine and was told she is to do it every day for the rest of her life as long as she is playing softball. Six weeks later she is throwing better than ever, harder than ever and her shoulder has never felt better.
I ruined my shoulder at age 13 trying to throw the farthest out of a group of boys. I didn't play travel ball and I wasn't a pitcher, but my shoulder still bothers me today over 30 years later and it has always bothered me when throwing. If I had gone to the Akron doctor you refer to, and I know who he is, he would have told me without a doubt it is overuse. That is always the answer that Dr. JC will give you.
All I'm saying most girls playing travel ball have had a sore arm or shoulder, even those that don't pitch. Show me an epidemic of arm and shoulder injuries,
verified to be caused by the pitching motion. I'm not saying they don't exist, but are they really caused by the pitching motion? In some cases, sure, in most cases not likely.
If we are really concerned about protecting the "children", then make masks mandatory for pitcher and corners like someone mentioned earlier. I don't think we are saving the masses by limiting pitching time.