So much good advice.
My son isn't a ball sport kid...he just turned 14 and has a Black belt in Ti qwan do and is the fastest freshman (19:45 for three miles) on his X-country squad.
He has told me that even though he was a bit apprehensive, that playing baseball was fun...not something he ever wants to do again, but he liked the experience.
My mantra is introduce, support and then let them tell you what the really want to do. But by all means, have fun with zippy expectations.