If the danger of throwing a curveball depends on the conditioning of the arm, then why is everyone saying that NO young players should throw curveballs? Everyone seems to be agreeing that if the arm is strong, then it shoud be fine while throwing a curveball.
I agree with SoCalDad. Those statistics are nothing more than a sample of pitchers who probably throw more and harder(more force) than the rest of pitchers that age. Those are two very important factors in arm injuries.
Kids who throw hard are more likely to hurt their arm, so lets make a rule that a pitcher can't throw above 60mph until he is 14! That should limit arm injuries!