You'll need present more information because it's difficult to judge this appropriately without seeing how you're performing your tests.

I'm intending to do some tests on this once I hit 80 as I've seen this comment at least three times now. I'm currently theorizing people are comparing capped ilvl 70 healers versus minimum (or even under gear) ilvl 80 healers and that's where the values feel off even though it isn't. A better comparison would be a min ilvl 70 healer versus min ilvl 80 healer to just see how much growth has occurred. Obviously, we can't compare a capped ilvl 70 versus capped ilvl 80 because we just aren't at that part of the expansion yet.