I've PvP'd with every class (sept hunter) and in bg's when you die and res, you get Spirit Heal so you can buff up quickly for free.
You get a similar thing at the start of a bg, and in this part as a warrior you can Battle Shout or Commanding Shout (or generally any ability that costs rage that doesn't require a target) at your hearts content.
Is there any reason why you cant do your buffs as a warrior when you have spirit heal, where as any other class you can use ANY mana using spell in this time period without it costing anything.
P.S I'm assuming its the same for bear druids.