Well you what is stated above is not entirely true. US Lacrosse age guidelines go U9, U11, U13, U15. And TLI goes U9, U10, U11, U12, U13, U14, etc. That means the even year teams should play the grad year teams determined by whatever the highest grade of any team member is. For example, a U10 team should play 2021 in a grad year tourney even if there is one 5th grader on the team not claim to be a 2022 team and justify it by saying there are older kids in 4th grade. A U10 team this summer (unless really good) should play in the B division of a U based tourney. I have to say I agree with age based requirements and like the setup of TLI. However, US lacrosse for some reason goes with a 24 month age spread, which has always puzzled me.

http://www.uslacrosse.org/rules/age-eligibility-guidelines.aspx