I see poster is in CA. So, to those asking, it is totally normal to have tryouts in September. Many CA hs programs have baseball as a class. CIF rule is that at least one day of tryouts have to be after the first school day. (MANY are the weekend after that) We also have a pretty robust fall and winter (off) season with mini-unofficial leagues, scrimmages and tournaments (thank you mild winters) for HS programs. If your son wants to make the team next year he will absolutely need to come in above the bottom third of the team. He needs to keep in mind not only does he have to improve, he has to improve at a rate better than everyone else on the team to gain positions... So depending how intense your high school program is, you may need to find a fairly active travel ball program with a solid winter option (be careful, many say they have winter but because certain HS programs are so time intensive, they don't do much with their travel program.). Our travel program offers practices and games during the fall and winter but many of the players that are at the super competitive HS programs miss a lot and come back for tournaments or events. Yesterday son had baseball starting at 1:15 (6th period) went until 3:30. HS team weights from 4-5:30 and then had to muster the energy to go to 7pm pitcher workout for travel, several other boys bailed on the travel practice. It's just something to be careful of when looking for a travel program. And for your son to keep in mind. Lucky for you, I'm guessing this feeder team the other boys were on probably cut back the more the HS team works. Either way, you son is going to need to work HARD. He needs a good weight training program and a good hitting instructor. It can be done but it will not be easy, and it's certainly not a matter of hitting off a tee a couple times a week and thinking things will be different next year.
Best of luck.