I'm not in the middle of this, but my understanding was that New [lacrosse] public schools placed kids in grades based on the calendar year. So that, for example, a kid with a November birthday would be in the same grade as a kid born 6 months early in May.

By contrast, U.S. Lacrosse uses a September 1st cutoff, which is I think is pretty similar to the breakpoint many parents use for which grade their kids attend. (Although I understand it is more common now for parents to "hold back" a boy born in July or August than back in my grade school days.)

This would explain why New [lacrosse] would field grade-based teams, so they aren't splitting up kids from their friends in their same grade. This would also mean that NY grade-based teams are, on average, a little bit younger than most grade-based teams.

That's quite a different purpose than going to grade-based teams so that you can have pre-September 1st kids on your team and not have to worry about U.S. Lacrosse age rules. While I doubt anyone cares about a kid with an August 28th birthday "playing down", it makes a pretty significant difference if a kid is born much earlier than that.

Besides eventual recruiting issues more pertinent to LI and Md, my non-hotbed program going to grade-based teams in order to let more kids per grade be on the "A" team, keep kids together and, most significantly, offer the best and safest competition by playing kids your own age. Stacking your grade based team with older kids takes away from this last objective, but it's still safer for my 6th graders to play "old" 6th graders than it is to play 7th graders - so it's hard to care too much.

I agree that I think it's ridiculous to hold back developmentally-normal younger kids for athletic reasons, but it seems incredibly prevalent as kids jump to private HS's across the country, certainly not just for lacrosse. I have to think many of those parents are not paying "retail" tuition.