Originally Posted by Bashiok
Most people on PvP realms like having a faction advantage and choose their server or move to servers specifically for that reason, which makes evening it out fairly difficult. There also tends to be a faction imbalance on PvP vs. PvE realms, where PvP realms tend to be Horde heavy and PvE tend to be Alliance heavy. So when we connect a few low-pop PvP realms together it's somewhat likely to only be able to be matching imbalanced realms with imbalanced realms. Considering the desire for a faction advantage, even if we did achieve a balance I'm honestly not sure how long it would last. In any case, with Connected Realms both sides will be getting more players, and bringing up the amount of people on each realm is the goal.
Connected Realms are a complex process, we have a lot of data, we're taking our time, and we're taking a lot of factors into account to provide the best possible end-result we can. Faction balance is one of those factors, but it's definitely far more nuanced a problem.