You said.. "he has now sprouted to 6 2, and 145 lbs (sopping wet). Put a ball in his hand and he looks like an athlete,.."
If he is a 2019 who is 6'2" and athletic with a ball in his hand, he shouldn't need any stories. Most would kill to be 6'2" as a soph. He's still young enough that anything can happen.
I've told the story recently of a pitcher that came out of our HS program... threw a grand total of 7+ innings and hit .091 as a sophomore (playing most of the season at JV), was decent but not a standout as a junior (3.2 ERA in a typical Calif. HS league), then outstanding as a senior. He got late attention at a D1, still took a while to fully develop his velo, excelled as a redshirt sophomore, and was drafted in the second round last month with a very healthy signing bonus.
As far as the soph to jr to senior progression in HS, this player's path is quite typical. I would say, on average, the players who eventually contribute to V as starters (and go on to play at some college level) take a path very similar. I could cite countless examples. Early development is the exception, not the norm.
Four of our pitchers this past year ...
1 - was in JV prior (soph) year, couldn't throw strikes. With a lot of work wound up 10-1 as a junior with an ERA around 2.00 for a playoff V team.
2. - a senior who was decent as a junior but was all arm and was always sore for 4+ days after a start. With a lot of work, completely retooled, became our go-to ace, arm stayed healthy and fresh, was recruited by and will be attending a very competitive D3.
3. - a junior who came back into baseball after sitting a year to play football. With a lot of work, was brought up to V and became our #3 starter by end of season... was very successful, also with a low 2's ERA. With a lot of work, he stands to be one of our top 2 rotation guys next spring.
4. - a junior, got about 14 IP as a soph, gave up a lot of hits and walks. Worked pretty hard to develop, only to have an injury prevent him from getting more mound time. He is already working really hard and I have no doubt that he will be a top arm for us as a senior and more than capable of taking his skill set to the next level as a P or as a position player.