I don't think you could pick a cutoff date that would be 100% fair to everyone. If you did it on Jan 1st then a bunch of kids would be changing up during the season. So it prob has to do with w/ the likely hood that the kids involved would be less than 6 months older than the age group they are in. As you go through the system you see how this eventually works out. It just seems a little daunting when they are younger. Imagine if your wrestler had a Dec 31st birthday, how that would work into the equation.