So what is it doing in the battleground finder? This is all part of Blizzard's renewed efforts to bring much-needed changes to PvP. The plan behind this alteration is to balance the number of healers on each side of a battleground, to within a tolerance of one, as Blizzard PvP Designer Brian Holinka clarifies on Twitter. What does this mean? The plan is that, while there's no set number of healers for a battleground, there should never be more than a difference of one healer between two teams in a random battleground. Gone are the days of four healers on one team and none on the other, now, if one team has two healers, the other will either have one, or three. If one team has five healers, the other will have either six or four.
While my PTR shaman can't choose it, the tank selector is still active, for now at least. Certainly, there are several battlegrounds in the random queue where a tank isn't really a useful addition to a team, and so far we haven't seen any specific mention of an attempt to balance tank numbers, but it's possible that, in a flag-capture battleground like Warsong Gulch, there is an attempt to get each team a tank.