Our Little League is getting smaller because they recently started a try out program that runs from about third grade through just prior to high school. It seems to be working — most kids play both for a couple of years, and then sort themselves into "going to play in the future so I'll just do travel" and "this is a fun hobby, no pressure, I'll do little league."
As for high school, we too do not have try outs. We probably could, but there's a no cut policy. So we have lots of kids on the team, and eventually some leave cause they get no playing time. Others find a role keeping stats, cheering on their teammates, or chasing foul balls and hanging out with their friends. One kid had been a gymnast. His role was doing a back flip after every win. Weirdly, the boys who played said they really wanted to win just to see the back flip.
We have about 20,000 in our town.