Section 2 - PVP Power
PVP Power is a relatively new stat introduced to the game in Mists of Pandaria which acts as the offensive compliment to Resilience. The idea behind this new stat is to encourage players to use PVP gear in PVP by putting major PVP-only offensive gains onto PVP gear (or in the case of healers, healing gains). PVP Power increases all damage done to players (under all circumstances), and healing done (while outside PVE-instances), by a percentage that increases based on how much PVP Power rating you have. The amount of each bonus you get is also dependent on your class and spec.
-Healing specs receive 100% of the healing bonus but 0% of the damage bonus
-All other specs receive 100% of the damage bonus and a partial healing bonus depending on class.
-Damage specs for Druids, Monks, Paladins, Priests, and Shamans receive a 70% healing bonus.
-All other specializations and classes (including tanking) receive a 40% bonus to healing from PvP Power.
PVP Power is currently the primary differentiator between PVP gear and PVE gear. It is a "free" stat on PVP gear, meaning it is not factored into the item's stat budget. As a result when comparing PVP items to PVE items of the same item level all the general-purpose stats should be equivalent but the PVP gear will have PVP Power on it as well making it a better choice for PVP. This fact is particularly important due to the presence of item level limits in all instanced PVP. The item level limits change with each season, but their purpose is to limit the item level of PVE gear to be equal to or lower than the item level of the current season's PVP gear. These two factors together generally ensure that the current season's PVP gear is always the best gear for instanced PVP. However the item level limits do not function in the open world, so in world PVP a player in the latest heroic raiding gear will likely (and unfortunately) have a large gear advantage.Section 2A - The Absolute vs Relative Returns of PVP Power
PVP Power's scaling is very straight forward; it has linear returns when looking at it in an absolute sense, adding 400 PVP Power will always give you another +1% damage or healing in PVP depending on your spec. So every additional point of PVP Power will increase your damage/healing by the same amount. However I have seen some players around the forums describing PVP Power as having diminishing returns, and they are correct to an extent.
If you evaluate the returns of PVP Power in a relative sense it does have diminishing returns, going from 0%-1% will give you the same absolute damage increase as going from 30-31%, but in the latter case that damage increase is smaller relative to the damage you are already doing. Virtually everything in the game operates the same way. Think about primary stats for example; +3000 strength would give a warrior a pretty nice bump in damage right now. However if Blizzard said "Hey we like you random warrior!" and bumped their strength up to 100,000 then that +3000 strength would suddenly be worth a lot less to them even though it would still increase their damage by the same amount. The reality is that in order for a stat to offer you consistent relative gains as you gear up the stat would need to have increasing absolute returns, in other words it would need to give you more and more damage or healing the more of it you got. (For more info on absolute vs relative valuation see Appendix A)
Now it is time to look at the actual scaling of PVP power, which is shown in the graph below.
As shown in this graph PVP Power's returns are perfectly linear. You gain either +1% damage or healing for every 400 PVP Power you have, this is also the “baseline” upon which the reduced healing bonuses for non-healing spec are based. The red line shows the healing bonus for hybrids (70% of baseline), and the yellow line shows the healing bonus for everyone else (40% of baseline).