I think you folks should pay a little more attention to what Texan is saying; he is right on.
While all may argue about whether throwing the deuce will harm a youngsters arm/shoulder/elbow, I think that data shows that IT DOES. There are no justifiable reasons to have him throw one - equating it to a basketball player learning to shoot with is left hand is ridiculous - anybody ever give any evidence that shooting left handed too soon will eventually lead to surgery??
Throwing #2 that early is simply a way to have the end justify the means - there is no reason for it; yeah, every kid is different, but the fact remains that it doesn't matter how many batters a pitcher gets out with Uncle Charlie when he is 9, or how many mythical championships he can win that way. What matters is what kind of arm he has left to compete at the HS level and beyond.
My son threw nothing but FB and Change [started pitching at 9]..he learned to throw a slider from a former major leaguer at age 15 [he throws a slider b/c his pitching coach decided that it was best [as opposed to a CB] based on his arm slot for his FB - nobody is talking about this. Besides the slider being harder to pickup by the batter b/c it resembles the FB so much, he has better repitition/muscle memory, since his arm slot is ALWAYS THE SAME, which include his change-up [his best pitch].
As a HS soph, he has already had exceptional success in Varsity/American Legion ball.
But wait, the best part??? HE HAS NEVER NEVER NEVER HAD A SORE ARM/SHOULDER/ELBOW!!!
Why chance it?? All the kids on my son's team that were throwing the deuce at 9-10, (my boy begging to learn one) - only one is still an effective pitcher [and he experiences frequent elbow pain] - the rest are watching!!
DON'T DO IT