http://www.diablofans.com/blizz-tracker/topic/55927-firebirds-finery-bonus-temporarily-disabled
Addendum:
I need to make it clear that I am not pleased with how they made this change (how the set initially does less damage while it is ramping up compared to how it was working on the PTR). Yes, I know that everything on the PTR is subject to change.
My issue though is they obviously knew that the way that the set was ramping up damage on the PTR, was not how they wanted it to work (yet they never bothered rolling out a fix on the PTR so that players would have a better idea as to how the set is supposed to perform). Instead, it was a misleading preview.
This amidst all the other issues like hydra not working/scaling properly with the set, teleport still being awful (pathing issues still persist), mirror images AI still working poorly. Then you have stuff like Electrify that still procs way too often. Oh, they can hotfix player related issues really quickly but don’t do jack with lot of the environment/monster related ones.
Just more ammo as to why this dev/design team is full of fail.