Averages will fluctuate until you have played enough ranked rounds at that particular tier to saturate your average. For Tour Pro I think it is 25 ranked rounds.
Ranked Rounds do not include any played on Bandon Dunes, The Best of Par 3, The Best of Par 5, any played on Custom Courses (Tournaments created by your CC).
Once you have played those 25 Ranked Rounds, your average will only move down. Once it is less than or equal to 67 you will move up to Master tier, where it starts all over again, only it takes more ranked rounds, and a lower average to move up again. Also the game gets a bit harder when you tier up.
Good Luck and enjoy the game.