Krak- good point. There's only so much we can control so why not spend that energy working on things we can control. Things like grades, hitting, working on baseball skills. In retrospect I am the best worryier(is this a word?) I know and much of it was needless worrying. And quite often every player has what may be seen as drawbacks by many people and they can work hard to prove these people wrong. Unfortunately sometimes the shorter players have to work harder and be better than their taller teammates to get noticed.
And, sometimes you have to ignore these "helpful" peoples advice/comments as they just don't know what they're talking about but still freely throw around their advice and comments. Great to prove them wrong isn't it? Also it's interesting to look back and see that some players that were huge @ 13 years old stopped growing and are no longer the best players. Some mature early and it does give them a big advantage but as you say let nature take it's course.