that's pretty damn far for a 3rd grader. i'm sure there are some kids that can, but we're talking about a select few. i coach little league and this last season on my oldest son's team we had a boy named zach, our first baseman, this kid could swing. he was only 6 1/2 and was hitting 100+.
i've noticed 2 very common denominators with kids like this:
1. older brothers
2. at least one summer at baseball camp
we had a boy who had never picked up a bat before we started pre-season practice and by our 5th or 6th game was hitting better than half our league. that was just pure natural god given talent. well, that and my coaching skills....
also, the pitching plays a huge part. in younger pony leagues pitching plays a much larger role in the outcome. so many kids just haven't developed the ability to hit locations with speed, which is what's typically needed to hit a ball as far as you witnessed. we coach pitched to most of our kids, which for obvious reasons is a completely different dynamic. i know what pitch each kid likes and can hit well, duh, opposite of how it's supposed to work.