The Tour Masters with the higher averages...like myself...are mostly players who have been here a while. Back in September when the Tier format expanded, the highest ranked tier was divided in 2. The better half was upgraded to Legend and the lesser group upgraded to Tour Master. Having just turned Old Master and fairing quite poorly, I was rewarded the upgrade to even harder green speeds and the title of Tour Master.
As far as advancing...WGT has their formula. Just keep playing well and you will be rewarded in due time.
Happy Golfing
Joe.
PS Back in June was the US Open Qualifier at Oakmont...that screwed up a lot of averages as well