It can be very annoying when one of the teams has 4 healers and the other one has none. It would be nice if battleground queues could detect roles and balance the teams better. (I have encountered battlegrounds with as many as 11 healers (both teams together) which is ridiculous and makes for a very frustrating gameplay.
I know you can change dual talents inside battlegrounds but that doesn't happen often enought to be a problem.