Hi there.

Got in Emerald Nightmare last night and downed 6/7 normal with my guardian druid
After the raid, the other tank and the raidleader approached me saying that I wasn't playing any good, seeing as I took alot of healing and overhealing. I was never in any real danger of dying as I had top priority on ironfur and using my cooldowns wisely.
I tried to explain that this was because of my mastery stacking, that I do take more healing and the heals done on me does more, therefore the overhealing is high because the crits are higher. 
Is this just me being wrong, or is this me being bad?