Positions in High School?

In my experience it could be a combination of all of that. During tryouts, the players will gravitate to positions where they feel most comfortable and where they have the best chance. There will be too many SS's and 1B's almost for sure. Too few RFers and LFers. The coaches will select players for their team based more on athletic and raw baseball ability than anything else and they will then begin to move players around to fit the overall puzzle. Some of the SS's will move to 2B or 3B or even OF. To be a 1B you better be able to hit and to be an OFer you better have a little speed or be able to hit.

In the end, the starters will likely be 9 of the top 10 or 11 hitters on the team, put in positions that optimize the defense as best as possible.

I agree with justbaseball..all the above and maybe a few more.
The coach will evaluate the players and will move them to the positions that will best satisfy the needs of the team. Most high school baseball coaches have to make do from what he has. Unlike a summer team, the coach does not have the ability to recruit his team's specific needs.

In my experience as a player, it seems to me that in little league, the players in the corner outfield are usually the worst players in the starting lineup. The stars go to SS, C and 1B and the good defenders go to 3B and CF and the small kid goes to 2B. Pitchers are the kids who can just throw hard and somewhat accurate. When the freshman tryouts seem to come, most kids, as said before do gravitate to SS and 1B and alot of kids will throw so hard to impress upon the coaches. Kids are not used to throwing from the corner outfield and that is why most kids get cut. The players that stay are the ones who practice gaining arm strength. I don't know what it is like down there, but in Alaska, long toss is not emphasized at ALL until HS. So all of you young bucks reading here, do long toss and learn how to play LF and RF. Even if you don't end up playing there, how will it hurt to learn how. It just gives you more flexibility with the coaches and that is what will keep you on the team if there is a position battle.