Seems pretty simple and fair to me.
(1) The players you were sending appeared to be just bonus whores, or players not playing much at all, hence the initial bump to $30.
(2) To earn the CPA for a player, each player has to earn 100 poker points, which you earn by playing there. So if you sent 10 players, Players 1,2 and 3 have all made 100+ points, while the rest haven’t.