First: The armor nerf. The armor bonus provided by Blood Presence was lower by 30% to 30%.
This is a nerf in current content and leaves us with lower armor than pallies and Warriors.
However: The nerf was obviously intended for cataclysm content, since shield provide a rough 30% increase of armor for a warrior/pally.
Their armor without a shield in raiding gear is somewhere between 30-35k and a shield provides around 11k armor
http://www.wowhead.com/item=59444
So the "nerf" brought our armor in line with them.