Thought I'd start a thread which has emerged on the 2017 HS thread.
(OK, first, S grew up in Southern Cal and the weather does allow baseball just a bit more than the NE.)
To me (all done and through), it's all about the extra work. My position is simple: building baseball skill is an incremental process and the more you do it, the more incremental progress a kid makes. Some kids have a head start; some are bigger; some finished growing early and have coordination, but eventually most fall within the bell curve of potential. The separator (i.e., reaching that potential) is extra work - and very few put in enough to separate them from the crowd; and only those separated play at the next level. (In other words, kids don't reach their final baseball potential unless they do that extra work.)
How to do it? That is the issue/problem. And each family needs to figure out how - how, after focusing on academics, is there enough time to work extra? But there are enough kids out there who do figure it out.
(One story that used to make the rounds here was about Alan Trammel (great MLB SS) who carried his glove with him where ever he went and figured out ways to work on his game.)