Also the absorb shouldnt be affected by pvp power in my opinion. Only the necrotic strike DMG.   
http://us.battle.net/wow/en/forum/topic/7004453720 
http://www.mmo-champion.com/threads/1472661-Does-Battle-Farigue-PvP-Power-affect-Necrotic-Strike-debuff 
http://www.mmo-champion.com/threads/1472661-Does-Battle-Farigue-PvP-Power-affect-Necrotic-Strike-debuff   
So in my opinion it also make sense. PvP power only increase your DMG, not the absorb.   
But as i said, im not sure, thats just a suggestion.