Lets be clear here. If a U-15 player plays U-13 he is not breaking the rules if he is eligible by age to play U-13 but happens to be good enough to play U-15 at other tournaments.

For example my boy Johnny was born on September 1st 1999. Based on age he is a U-13 player in 2012.

Most boys his age (Aug/Sep '99 births) are in 7th grade.
Knowing I want him to get a Lacrosse scholarship I red-shirted him as a Kindergartener. You would think he'd be in 6th grade, but as it turns out Johnny is not too bright and got left back a few years ago so he is only in 5th grade.

Fortunately, he really is a good Laxer. I always thought Ivy Leaguers were too stuffy. I am therefore not concerned with Johnny's academic problems (ACC Lacrosse is better anyhow and I hear those southern schools like Duke and UVA have very relaxed academic standards).

Even though he 2.5 years older than his teammates he plays on his 5th grade 2019 team and does really well.

When it comes to age based tournies he is good enough to play U-15, but aged for U-13. Even though he usually rosters w/ a U-15 squad is it wrong for him to roster at some tourneys as a U-13?

Assuming he does a PG year and red-shirts a year at UVA he will be 26 when he graduates. Thanks to lacrosse he will have given up only 4 years of earning potential to get his $5K per year partial scholarship. In 2012 however, I do not want him accused of cheating for occasionally playing U-13.