They also recently changed BG's so they won't start until each side has a full queue.

That is not to say there will be a full starting complement in each, by the time the game starts.
But no one will get the button to enter the BG, until there are enough for both sides to receive it at once.
People will still queue for two BG's and take one and ignore the other.
Or leave a BG in progress or before it has started.

You can still have an arena member queue you for a skirmish.
To get you out of a BG you don't want to be in, without getting deserter.