An obvious nerf, right? Blizzard doesn't seem to be so sure. Players say that there was a reason rank five gave 6% chance to crit, and it was probably to balance the ability with other abilities in endgame. But Neth says that though it is a nerf, the devs did it just to bring the values in line with other similar ranked talents. Even giving Neth the benefit of the doubt on the devs' decision, that seems really unlikely-- no one would "accidentally" count 1, 2, 3, 4, 6. Clearly the extra percentage crit chance was in there for a reason, and the devs shouldn't change it back unless Shamans really are critting too much (and by all accounts, they are not).
It seems like a lot of whining over a small issue (and yes, that could be said about all of this Shaman business), but once again not only is Blizzard not clear on their communication, but they continue to mangle Shaman relations-- in a patch where Elemental Shamans are finally hoping for a buff, the devs decide instead to nerf one of their biggest talents, supposedly to fix a mathematical bug. If the devs suddenly said that Fel Concentration was getting nerfed to 10%, 20%, 30%, 40%, and 50% (rather than the 14%-70% it's at now) because those numbers were more "in line," Warlocks would throw a fit. And that's exactly why Shamans are so unhappy right now.