I had had the same question as several other people. This information does help explain things a lot. Thank you. But as per game design, it is a disaster.
I am a Tour Pro. My average is just over 69. In my entire time of playing WGT (at least 200 rounds), I have maybe 7 times shot 69 or better. My lowest ever score is a 67 on St. Andrews. I wish I were better, but lots of 2-putts and 2 or 3 errant drives per round, and my real average is probably about a 75. Again, I have only show under my "average" a handful of times. Eventually, I will get another few lucky/good rounds and I will be tiered into a Master (because my average only goes lower, never higher). At that point, I will be lucky to ever break even par again on any course. And once I tier up, I can never return, even if the tier is too hard for the consistent state of my game. So I have a complete disincentive to ever play the easier courses, or if I do play them, I dread having a good round. It should be the opposite--players should be excited about good rounds and not have to think about (essentially) getting penalized for them.
I want to stay at Tour Pro until or unless my game improves enough that I can be competitive as a Master. This isn't a case of my sandbagging--my given "average" is clearly much lower than my actual average is, but WGT doesn't show the 10 games where I shoot in the 70's, only the 1 game where I shoot a 68 and it lowers me. My goal is not to level up as high as I can and shoot a bunch of 87's as a "Legend" someday. My goal is to be able to play a good, relaxing round of (virtual) golf at a level where I am comfortable. I understand the need to prevent Legend-caliber players from manufacturing "80 averages" and staying in lower tiers so they can thoroughly dominate inferior competition. But is this REALLY the best way to do things? To force players on the bubble of over-tiering into hoping that they play poorly enough to just barely avoid walking through a one-way door to a needlessly harder game?