Sorry, but this is an absolutely terrible way to judge overall balance. You are using the most extreme examples of a spec being weak in a particular role and comparing it to another class that excels in that same role.
https://www.warcraftlogs.com/zone/st...7&difficulty=4
That is a far more realistic view of class balance, and to be honest, that is pretty damn good. Asking for, and even expecting 100% perfectly balanced dps any given tier has never happened in the history of this (or any) game and will N-E-V-E-R happen.
Arcane needed some help, which they got. Shadow priest in particular could probably use a small nerf but pretty much everything else is well within the "close enough" range where getting upset over "unbalanced classes" makes you look like a complete moron. This entire thread reeks of players blaming their class/spec being terrible for their under performance in the new raid instead of looking at themselves and trying to figure out what they are doing wrong.