They gave up on it before this. The rankers said they would leave if they couldn’t continue to do premades in it and then they left. The 90% win rate is a direct result of these players no longer queuing for the BG.
There are only twos ways to really fix this. 1 is to increase the HPH gained making a longer game worth it for rankers with instant queues to join in and play the BG. 2 is to allow premades to queue AV.
Personally I am for either one.