For any readers who don't know, Mists of Pandaria brought about a fairly substantial change in PvP gear. Resilience and Spell Penetration were removed, and replaced with two shiny new stats: PvP Power and PvP Resilience. PvP Resilience is essentially the same as the old Resilience stat, reducing your damage taken from other players. It's active all the time, whenever you're wearing your PvP gear.
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