This is elite level 8th grade lacrosse, which means roughly 1/3 of the kids are holdbacks, 1/3 are on age but hit puberty early and can compete physically with the holdbacks, and 1/3 are very skilled on age kids, but lack the size and athleticism (for now) to keep up with kids in the first two categories. If your son is in the third category he can embrace the challenge and work harder, or drop down to the division below elite, where he will do great. But there ain’t no use in complaining, that’s just how it is.