The matchmaking in GAC is still broken I'm 3.2M getting bullied by like 5.5M GP in bronzium and my guildmate who is in carbonite is having the same issue;and we even faced people with 2-4 GLs. These have been common occurrences. people are sandbagging their rating purposely to go to the lower levels make lower GP players experience more miserable and bully or have consistent crystal rewards from 1st place rewards.
solution: everyone says bring back the GP brackets in GAC that's one solution. I think a simpler solution is to make each bracket of carbonite, bronzium, chromium, aurodiam etc. and the 1 through 5's have a GP that is the ideal CG recommends that higher GP's can not infiltrate lower brackets but would allow skillful players of lower GP to punch up but if knocked down they go back down as long as their GP is not above the threshold net sort of speak.