You should seek out the US Lacrosse representative or chapter for your area. They will spell out the differences between age vs class based teams. Typically, the class based teams are better than what you would think are their comparative team in age based. This is because the class based teams will almost always have a number of kids like yours. The class based teams will have a number of kids who are older than the age cutoff used by US Lacrosse. This leads to a physical and emotional advantage on the field. Also, US Lacrosse does not sanction teams to participate in their tournaments with kids over the age limit. If one child is older than the age cutoff, the team must play in the older division. If the club only lists graduation years, than the team will most likely have more than a few kids with ages like yours and the tournaments and leagues they play in will mostly be based on graduation years.