It's not that recently uncovered--I remember some knowledgeable person (Kenco?) mentioning it on this forum a very long time ago. It's just more talked-about now because of Paladins.

Believe someone discovered a while back, testing with a Rogue, that specials are on a two-roll system while white hits are on a single-roll. I don't of any detailed tests for ranged or spell.

So 2-roll means that first it has to hit, then it crits? i.e., for a player, using the conventions from post #1 here:

"roll 1" considers only M, P, D, B, and (C+H) is the residual (because players cannot crush, nor can we glance specials)

Then, if it's (C+H) then "roll 2" is
0% through C% = crit
C% through 100% = hit

Is that correct?

Yes, that's one of the reasons why no one takes Shield Spec for Shaman. Caster Shaman are pretty much the only type who use shields, but it's worthless since anything but auto-attack will prevent you from blocking.

Is that bit in the original post still correct? I thought rage normalization was more complicated than this.

No, it's out of date. I stuck a note at the beginning of the OP about how old it is.

EDIT: Ok, well, I tried to, but it won't let me, because the post is too long.