I never pitched one, but I caught a few no-nos. The kid must have had one hell of a catcher working with him. I hope your son bought his battery mate a steak and a beer after the game.
That was part of the amazing aspect. The starting catcher had a stomach ache at the beginning of the game. He caught the first inning. The second inning, as he was walking to the plate in full gear, he turned around and said. "I don't feel so good" and was sweating all over. So we had to put a kid back there who had never caught while the started visited the porcelain throne. I think he only actually caught 2 of the 18 pitches my kid threw that inning. But he chased on down and gunned the games only base runner down trying to steal 3rd. The runner hesitated and was out by a mile.
In between innings, I tried to coach the back up on proper positioning and giving a good target. When I told him to open the mitt up he said, "I don't want to do that because it hurts my hand when the ball hits it." I told him to try to catch it in the pocket instead of the palm.
BTW, the starter came back from the restroom a new man and took his position behind the plate for the 4th inning.
9 - 10 year olds are a lot of fun.