An article over at IGN.com tells us more about why and how the Empire is leading the warzones in SWTOR. IGN tells us: 6c6o6o
According to Gabe Amatangelo, lead PvP designer, Empire players beat Republic players in 53 percent of Voidstar and Old Republic’s most played Warzone, will also be included.
At some point in the future, BioWare will let players select which Warzone they want to play, though a timeline isn’t yet set. As it is now, when you queue up to enter a Warzone, you could be potentially dropped in any of the three.