Guess what - kids from the Dominican get sore arms and drop out of the game. Pitchers from the past got sore arms and dropped out of the game. A lot of Japanese kids develop sore arms and other injuries and drop out of the game. When I was in LL and Pony league kids threw complete games got sore arms and dropped out of the game. Guys who went to Jaeger develop sore arms and drop out of the game.
There is no one right way for every pitcher. Every pitcher is different and you have to experiment to see what works best for the individual. Not only that but they change as they grow.
I threw tennis balls when I was a kid and my arm always hurt afterwards. I threw complete games and my elbow ached toward the end of the game. Everyone is different, especially Nolan Ryan. I'd wait and see how their little experiment works out before you try it yourself. My guess is that they'll weed out some very good pitchers in the process of finding a few pitchers with rubber arms who may or may not have MLB talent.