Lore spiega in un suo intervento che il problema ha origine dal fatto che rimane possibile ai giocatori giocare in un'altra specializzazione una volta entrati nel campo di battaglia. Alcuni giocatori, che il sistema aveva considerato nei suoi calcoli come curatori, giocano dunque in un altro ruolo, sbilanciando le squadre. È pertanto in previsione una modifica, che probabilmente arriverà in Warlords of Draenor, che obbligherà i giocatori a giocare nel Campo di battaglia il ruolo che avevano selezionato durante la fase di accodamento.
Lore ha scrittoOur matchmaking system does its best to even out healers between teams in Random Battlegrounds. So if one team has 3 healers, it will do its best to match up them up against a team with a similar number. Maybe it's 2 or 4 instead of 3, but it's still relatively even in the grand scope of things.
When we see cases like the OP describes where one team has a much higher number of healers than the other, that's almost always due to players misusing the queue system. See, when you queue for a BG, the system assumes you intend to play the role you've queued for (or if you've selected both, that you'll play whatever role it assigns you). As we've investigated these cases of heavy healer imbalance, we've discovered that's not always the case.
Sometimes, a player will queue as both roles, but not play the one they're assigned (either because they didn't notice it, or simply chose to ignore it). Some players queue as healer with the intention of playing as DPS, under the (incorrect) assumption that it will speed up their queue times. In some extreme cases, players will specifically queue as DPS with the intention of playing healer and causing an imbalance.
To alleviate this and help ensure that groups have equal numbers of healers, we plan to lock players into specs that align with the role they were assigned when the queue popped. So, for example, a Shaman who only selects the Damage Dealer option when queuing will be forced to play as either Enhancement or Elemental once they're in the battleground. A Priest who selects Healer can choose to play as either Holy or Discipline, but not Shadow. And a Monk who selects both Healer and Damage Dealer and is assigned to heal will be forced to play Mistweaver.
Keep in mind that the system doesn't look for a set number of healers when it's setting up games -- all it's doing is trying to match up teams with roughly the same number. The goal isn't necessarily to ensure that every single game has 3 healers, it's just to make sure that it doesn't match a team with 4 healers up against a team who only has 1. When everyone's playing the roles they're expected to, it can be much more successful.