The World of Warcraft PTR is met with a lot of criticisms due to the fact that numerous balance changes led to further disappointments and even resulted to some classes to be virtually unplayable. Now, one of the developers of the game addressed most of the community's concern on the official forum and listed some of the team's plans on the upcoming character balance changes on the PTR.
World of Warcraft PTR: Character Balance Changes
According to Ornyx, the community manager, the team wanted to introduce a new talent which will allow protection warriors to have their autoattacks trigger Devastates rather than including it in their normal rotation. According to him, this change hopes to create a more "open playstyle" to players.
Since their announcement of bringing back the trap ability on all talents, Blizzard will still make Survival Hunter feel far more superior when it comes to the mastery of traps. In the next PTR update, Blizzard will include new passive abilities which will further enhance the Survival Hunter's mastery of traps. Furthermore, the devs will also add new talents to further augment the Survival Hunter's uses and viability of traps.
Lingering Insanity will be removed. The reason for this is that according to the developers, they wanted to adjust the pacing in a way that the strength of Voidform is at its peak at the near-end of the duration rather thatn before the start of the next one. Moreover, Mind Sear will be replaced with a Mind Flay passive which enables the latter to fulfill the same purpose of the former. Lastly, the team is currently tweaking on the decay rate of Surrender to Madness to properly balance out the ability.
One of the most criticized changes in the PTR was the Fire Mage class. The class was deemed to have undergone a major overhaul that made it almost useless in the current meta. 'Useless' in the sense that the class was rendered far more inferior from the prominent spec (frost) and also made it seemingly unviable in the Arenas as a whole. According to Blizzard, they're fully aware of the community's concerns and that they are hoping to improve the Fire Mage gameplay by adding its own element-themed shield, adjusting the damage of Fire's core spells (unspecified) and tweaking the effect of Critical Strikes on its contribution to the Overall damage of Combustion.
Note that these are just some of the classes that will undergo a major reworked in the upcoming PTR update. Blizzard further implied that they are currently working to address all of the issues around all classes in the game and that the above-mentioned classes aren't the only classes that will be changed next update.