There is nothing wrong with holdbacks/colleges delaying entry so that a kid will play college at age 20-24. The problem is not playing on-age in youth lacrosse. For the equivalent of 9th grade and below it should be based on birth year. After that, the elite players can go into a "junior" system, while the rest can still play on age. This is how I would set it up at least. For instance, this past summer I would have had a 2006 division, 2007 division, etc. Within such, I would have AA, A, B or whatever makes sense. Kids can always play up (a 2008 can play with the 2007s if that is what the parents and the team wants). For 2005 and higher, the best will be on a junior team at junior events playing with and against kids up through 2002. For kids not at that level of skill/athleticism - there can exist continued birth year divisions. Obviously, college scouting (at least for D1) will be at the junior events.