Looking at each of the compositions I've played extensively in battlegrounds, at one point or another.
-- 4x Elemental + 1x H.Paladin // 5x Elemental.
-- 5x Feral // 5x Boomkin
-- 4x DK + 1x Paladin.

I never have an issue getting out of combat to rez a fallen toon.
Of course I stick to the larger battlegrounds, heavily favoring AV.
In something like EotS, once enemies are taken at a base, but the graveyard hasn't capped... a rez is easy.
Once the graveyard is held, it is so close that releasing is the best option.
In AV at say Iceblood Graveyard before it has capped, with Stormpike as the nearest alliance graveyard... having a rezzer is infinitely preferable to being half the map away from those who died.