My 2017 son is a year ahead of yours, and goes to a large school in N. Dallas. Some thoughts based on conversations here and what we experienced:
There was a 7th period baseball conditioning class in the fall where they practiced and had games. Multiple teams were formed (I heard 4). My son played football, so he did not participate in the baseball class. Not everyone made these fall "teams". I assume they were varisty/jv. I think you pretty much had to be part of this program to make JV.
Tryouts in December/January. We had 1 varsity, 1 JV, and 2 Freshman teams (freshmen/sophs go to two different feeder schools and each has a Freshman team). Each of those had ~ 30 kids try out for Freshman, of which ~16 made the team. I would say 1/3 were serious travel kids, 1/3 were travel/talented rec kids, and 1/3 were strictly rec level experience.
Freshman teams practiced every day and played ~ 20 games. Due to the mix of player backgrounds, those practices didn't look as "intense" as a travel practice. I'm sure JV/Varsity was more intense as the competition continues to ratchet up. It looks to me like 50%-75% of the kids fall away at each step (Freshman tryout, Fresh to JV transition JV to Varsity transition). Some really good players are not going to make JV.
We had 2 Sophomores make Varsity. We had 0 Freshman make Varsity. We had ~ 4 Freshman on JV, who I think all went through fall program.
Since our Fresh/Sophs went to a different "feeder" school, they practice on their own field, had their own coach, and never saw/competed with the JV/Varsity players/coaches.
No travel ball during Spring, you pick it up back up for Summer. There was no pushing players to play travel by the coaches, but it's pretty obvious that you better be doing all you can to be in the 25% that will continue playing into JV.
I realize this may be a little different than your schools situation, but wanted to communicate one person's recent experience/observation in case it helped. If we had it to do over again, we would have definitely been in the fall class/program.