As it is now, Battlegrounds: Capture the Relic is no fun at all in 8v8.
The off-balance problem is extra strong because of linear nature of the game. The losing party quickly gets stuck in the spawning area with no possible reprieve.
Moreover the only way to get a significant score is by capturing the relic. There is only one and you can only get it 5 times, so you are competing with your team mates over that honour.
You can get a tiny bit of points by healing a relic carrier or hurting an enemy relic carrier. So as a healer, hopefully your team relic runner won't run back too fast and worst of all, as a goal keeper it's best to screw over your team by letting the opposing team get the relic, so you can hopefully kill them.
The score boards say it all, most people get out of CtR with zero points, maybe fifty or a hundred. So for BG quests, getting 1000 points is unlikely, winning the game is a coin toss what team you're in and participating 5 times is a dumb quest anyway.
So you have team game that punishes team play and will likely get you nowhere.
First off, the scoring should be revised to give everyone a stake in a team victory. Perhaps if a relic score gets everyone 50 points, that would already make a difference.
And maybe if there is some side way mechanic to break the usual off-balance situation... I can't really think of something... but that would be nice too.