As it is known alliance has more players than the horde, it wouldnt be a problem tho, its normal, but there's a problem PvP wise here. The ammount of PvPers between the two factions is really unbalanced. For example at this very moment there's 30+ queued alliances for random BG, whilst horde side has a big flat 0. Its been like this all day long and sometimes the difference is even bigger. So maybe you should consider giving faction change to horde for free for a couple of days. I mean im sure there would be players willing to transfer to horde to make PvP more interesting. I would do it first but i cant level up new character and dont have vote/donate points to transfer to a dead faction PvP wise.