I thought I'd contribute. With quick trial and error, here's the crazy math behind the 38% calculation.
(1-.29) * (1-0.06) * (1-0.04) * (1-0.04) )
Except that he mentioned adding elite damage % didn't change the value. I'm assuming he's going off of the in-game value and not the profile view though.
Additionally, this sort of calculation only makes sense for reduced damage from elites. Which doesn't necessarily mean it's wrong, but it certainly SHOULDN'T be the way blizzard does it.
Yup. But it's definitely how Blizzard displays it on the user profile at this time. Perhaps it's a bug?