Disable multiple battleground queues
Basically, population is too low to keep multiple queues enabled. Premades queue 3 bg's, can only join one. People are either slowpokes and don't leave queues as soon as they pop and only hide them (once inside a bg already) or keep the other queues up so they can start anew if they feel they are losing the bg. In any case, you get games that are temporarily 5, 6, 7..10 players in favour of a faction.
Surely this goes both ways and both factions have free games that start 13 v 2 for example, but why have this?