I actually created an account to agree with the guy above me. The problem with feral AOE is the player not the class. On 2-3 targets I'm consistently #1 in DPS in mythics and ST I'm always #1. My player name is Nuzi-Proudmoore
Aoe Rotation (2-3 targets 300k-450k sustained DPS)
Open on main target with rake > thrash > Brutal slash to 5 combo points > Rip
Cast PS
On remaining targets I apply rake and then build 5 cp and apply Rip to those targets.
Use brutal slash on CD
Maintain Thrash bleed
Win.
Aoe rotation (4+ targets)
Good luck!
But seriously.
Use your standard opener on the kill target and spam brutal slash and thrash until 5 cp and keep casting Rip on mobs.
Thing you need to accept on 4+ mob packs. You will not be able to keep bleeds up on every target and you'll only manage to keep Rip up on 3 targets simultaneously and part of that is luck (It is possible to get Rip going on 4 targets but it'll only be for a few seconds before the 1st target Rip falls off).
Things to keep in mind in AOE situations is our kit isn't made to AOE. We are a predators! We hunt 1 target, we bloody 1 target, and we kill 1 target. No-one can beat you as feral equivalently geared and skilled single target. No class can under normal circumstances unless they get the planets to align and RNJesus blesses them with luck and takes a shit on you.
So yes, most often then not you will be behind in AOE. Accept your fate and do your job. Kill the most dangerous mob in the pack and follow that order.
Edit: The biggest problem I see with ferals struggling in dungeons (normal, heroic, and mythic) is their talents and expectations.
For dungeons your talents should be:
T1- Predator
T2- Flavor pick (Doesn't matter)
T3- Flavor pick here aswell (Anyone who says otherwise needs to stop staring at sims and actually become a human and play the class. Choose whichever of the 3 you feel most relevant at the start of the instance. I find myself going guardian with under-performing tanks (DH, brewmasters, etc) and so on and so forth for resto affinity. I'll go boomkin affinity if a boss has dangerous melee abilities to make it easier for myself.)
T4- Mighty Bash (No brainer)
T5- Incarnation or SoTF (Do not use Savage Roar in dungeons. There is no way to capitalize on it for trash (DPS loss in AOE) and without optimal gear it performs on par with Incarn ST and without the mind numbing rotation)
T6- Jagged Wounds
T7- Brutal Slash (I find this talent winning in just about every situation. Did Halls of Valor twice on mythic and found brutal slash to be a DPS gain over BT. With heavy managing of energy/rotation I did increase my dps with BT on single target but for the amount gained its just simpler to go with BS as it eases the rotation quite a bit.)