Several factors are in play here. First, Leveling has more to do with how much you play not how many rated rounds are played. Did you know, for example, that you can not only get points for a practice round, but you can get extra points for completing the round and you can earn the 880 points for consecutive days played point in a practice round as well.
As to staying in a tier when it looks like one should be advancing, this all came about after the change back in September. Before that, all you needed to do was play ranked rounds, post only your best scores and you moved up quickly. Now, playing more is a factor, averages change slowly... and although WGT has never admitted this, I believe playing more or exclusively in Country Club tournements hurts your chances of advancing...after all, the playing conditions are set by the tournament creator, not WGT.
Joey