Update 4/14/14: Here’s how the two stats work in 5.4.7:
- Resilience is now a base of 77% for level 90s, but remains at 40% for those under level 90.
- If you get the PvP trinket pair (any pair) there is an addition 3% resilience, for 80% total.
- PvP Power was nerfed hard in patch 5.3. The value of the stat was cut by a third and the value of the gems was cut in half. This means that PvP Power is useful for all classes, but the other stats will generally be better.
Update 9/5/13: See this post for the patch 5.4 PvP changes.
Here’s how the PvP Stats work
With Mists of Pandaria (patch 5+) there’s a new stat, PvP Power. This stat is much like Spell Power or Attack power, but applies only to PvP.
Basically the way it works is that PvP Power adds to the amount of damage or healing that you do to other players.
PvP Resilience is pretty much the same as before, except that all players will have a base of 40% PvP Resilience (77% for level 90s in 5.4.7) and any resilience on gear, gems, or enchants will add to that.
PvP power is a straight damage add and PvP Resilience is a straight damage reduction, so they might seem to directly counter each other. For example 1% of PvP Power negating 1% of PvP Resilience. This isn’t really the case. PvP Power adds a certain amount to your PvP damage and that is what is launched at the opponent. PvP Resilience then reduces the incoming damage by X percent.
PvP Resilience will be found on lower level PvP gear and PvP Power will be found on all of the high level gear. With the 5.3 nerfs you will not need to stack more of it. The PvP Power on you gear will be enough.
Arena Junkies has a long and detailed article on how these two stats work and play off of each other. I think he has his math wrong in the first section of that article, the progression is linear, not logarithmic. This only means that each point of Resilience counts for about the same amount as the previous point, rather than each point counting for more than the previous point.
The rest of the article is fine and will really fill you in on how it all works, even though it was written for an earlier patch.
Go here to read it: Mists PvP Power and Resilience Guide