Top 25% is fairly well positioned if your son is in 8th grade in my opinion. If your son is 6th grade, very different story as I would anticipate a lot of roster turnover. And new players that get added in MS and HS are all typically clearly obvious upgrades.

New players trickle in HS (much more 9th than 10th from what i have seen), but at that point usually the bottom 5 or so are the ones looking over their shoulder primarily... not the top 5! Sometimes those kids choose to leave to focus on other sports or realize clearly where there are given where they are in the depth chart with respect to playing time.

If your son stays at a top club - eg Crabs, Hawks, FCA etc. and does manage to be 1 or 2 in his position group through HS he has all the exposure he needs. To achieve that its just a question of making sure he develops as fast as the kids playing MIAA A conference (not easy in my opinion - and will require a plan). From there, depends on your kids work ethic and motivation.