When you queue for battlegrounds you have three options.
Deathmatch queues you for deathmatch.
Flag games queues you for Capture the Relic and Chaosball.
Land Grab queues you for Domination and Crazy King.
Why does it have to group certain game modes together. Some people dont want to play x game mode but get forced into those games queuing for the one they actually want to play. I will use myself as an example. I am only playing battlegrounds for the achievements that unlock a dye color or a achievement housing item. While working on those I had to kill relic holders in Capture the Relic but was getting queued into Chaosball. A game I had no desire to play.
Now for the next issue which has been around for years...
This achievement is still not working... after years of people saying its not working...
Crazy King flag captures do not go towards the flag captures in this achievement. That means only Domination rounds can get you this achievement. Couple this with how it forces you to queue for games you dont care about and it equals a lot of leaving games before they start and logging off to play other games or do other things until you get bored enough to come back to this mess of a system and try again.
I can already hear people defending this system with the "who cares about achievements" argument but even you must agree that forcing people to queue for games they dont want to play is stupid... just separate the game types. They always pop with 30 seconds anyways... so it wont hurt much to move all the game modes to their own queue. Those who want to play any game mode will still pop just as fast since they will select them all anyways...