Healing can make a huge difference in pvp too.

The biggest variable in rated battlegrounds, seems to be: the side with the more healing wins.
Probably going to be the same in normal battlegrounds too.

When you went healing, was it 4x Disc or 4x Holy?

Playing four of ten or four of fifteen will help in the lower (sized) battlegrounds.
You're less of the total team, compared to a five box.
Can you still blow up single classes with four healers?
Smite/Penance x4, Mindblast, SW: Death, etc?