Hi bigdog,
Your scoring average takes into account many factors and one of those is the frequency of play. If you only play a stroke play round once in a while your promotion # will be slightly lower than the average. If you take a look at the score histories for the players with these averages you'll see that many of them go months between rounds. If they were to come back and shoot 2 or 3 rounds in a row they would be promoted since the frequency of play and the amount of scores that can be weighted increases.
You can find a more detailed explanation here.