You do realize that many sports are setup this way now correct? Girls club lacrosse has been for years. AAU basketball has been for years. I am going out on a limb here and saying that most kids that are older in AAU are not MIAA holdbacks. Are they a special select group also?

This is from AAU's website

The AAU is a grade based organization.  Each grade division consists of a 24 month age window which determines an
athletes’ participation in that division.  If an athletes’ age is outside the 24 month window for their grade, the athlete
must play up to the grade division that is normal and customary for their age.  If an athlete is in any grade above what is
normal and customary for their age, an athlete may play down provided they meet the established criteria listed in the
chart below.