I dunno man… I think this might be in your head some. If anything, it has to do with gear and RNGeezus.
I’ve crushed some Horde warriors in BGs (removing 50%+ health in a global) with my crappy gear.) I’m pretty sure they rolled in wearing leather. On the other hand, I did lile 3k damage in a global on clothie and it hardly dented their health (probably a warlock with PvP/stam gear.)
Sometimes I feel tanky ad hell, and other times I get dropped before I can react.