Yeah some good conferences and teams were excluded.
"Note: No teams from the American, Atlantic 10, ACC, Big 12, Big East, Big Ten, Mountain West, Pac-12 or SEC were eligible. The same goes for Gonzaga and BYU out of the WCC."
My guess is they counted the P5 conferences as "Power" conferences. Then you have American, A10, Big East, and Mountain West as "Major" conferences. So the rest are counted as "Mid-Major "or "Small".