The Ranked Round / AVG method for tier advancement was the original base for advancement for the old Flash version. But when the Mobile game was created which included Coin matches it had to be changed to include players who only played those types of games.
You can get promoted (tiers) by playing Coin room, Match Play, Alt Shot, and Skin Games.
DO NOT ask how or for specifics because no one knows the algorithms that WGT uses to promote people this way, but the basic principle goes like this …
PLAY BETTER AND YOU’LL GET PROMOTED!!!