We, the members, have given many suggestions on what WGT can do to stop sandbagging. And it would stop because it wouldn't be worth their while to try and sandbag for long. We've told WGT (many times!!!) to go look at tournament leaderboards and check out the accounts of the low scorers... does not look like WGT are doing anything - they expect us to do it for them... a cop-out! We've told them to include other games and not just ranked stroke play games in tiering-up... does not look like WGT are doing anything here either. There have been other viable suggestions too... and not one of them has been implemented.
It would be very simple to include MPC's and Skins for credits into the calculation of a player's average and to add to the number of ranked rounds. Quite simply, count every ranked stroke play round, every MPC, and every skins game for credits as a qualifying round towards the number of rounds required to move up a tier. The calculation of the average with relation to ranked stroke play games can remain as it is now. For winning an MPC the average can be reduced depending on how big the win is; for instance, reduce 0.1 for a 1up win, 0.2 for 2up or 2&1, 0.3 for 3&2, etc. A loss should not affect the average either up or down, but a sandbagger wouldn't purposely go losing games. Something similar could also be applied for the number of skins won in a skins for credits game. With this in place, sandbaggers would very soon tier up and their fraudulent advantage would be wiped out. Non-credit games do not need to be counted as they are not hurting anyone.
Unfortunately, as I've already said, WGT have not implemented any ideas put forward to them, so they most likely won't do this one either.