Situation does vary greatly from program to program and kid to kid.
My son's HS has 3,050 students. Our '09 summer ball group was 27 freshmen, 22 JV, 22 Varsity. It was small because most of the seniors were playing Connie Mack or other elite leagues. In spring try-outs for JV/Varsity last year, there were about 75. Freshman had about 35 more.
My son was a 6'2" 185lb LHP when he tried out and last year became the first freshman ever to be moved up beyond freshman for his freshman season. He pitched for the varsity, who finished in the final 4 of 5A-I and had 3 DI signings and a player drafted. Their final record was 25-9. Son was 3-1 with 3 saves.
Why was he moved up? They needed pitching and he could pitch.
The point? At our school, freshmen playing freshmen is the cardinal rule, not the kiss of death. My kid could fill a very unique need and got moved up. He had pitched against JC kids in the fall of his 9th grade year and pitched very well in the AZ Sophomore Classic. He'd proven, through advanced travel ball, that he could get older, more talented hitters out, so he got a chance.
Don't think the HS coach didn't consult local area scouts before he made the choice to take a spot away from a Junior and send him to JV before he moved a freshman up. He so much as told me he'd consulted several scouts prior to making the decision.
Local area scouts don't attend recreational league games unless their car breaks down nearby and their cell phone battery is dead.
Flip side is that his freshman buddies all hit 3-7 HRs. He got exactly 1 AB at varsity and 8 plate appearances at JV (playing 2 games) going 3-4 with 4 BB's. This part was very frustrating.
Moral of the story, put your kid in the situation where he can flourish. In a big school, that may be freshman. In a medium\small school, that may be JV or Varsity. In my kid's place, he projects as a LHP. Getting exposure on a great team 'got him on the radar' and so it was all worth it. He'll get lots of ABs this fall to catch up.
If the kid can play, the coach will find him...