Probably both. The Terps probably had little turnover. They also most likely contacted the kids they want for their B team (Wolverines) and told them they would get an invite. If you make the Terps that is a great team. Wolverines, not so much.
They will sell them with the, "With the new additions like your son, we will be able to beat most of the other groups A teams". Just like they said last year. 2 years ago their A and B team practiced together and got very similar attention and practiced together. Then the A team parents complained about practicing with the "B" team and last year it was a different deal. Buyer beware.