After earning exalted a few days after patch 5.04 went live I went to start the quest chain that would reward the Battle Tabard of the Defilers.
The quest chain was missing, so I submitted a ticket and checked the bug forums for a thread.
It appears the quest chain and in turn the tabard we're removed.
There hasn't been an official response from a blue regarding this matter though based on responses from several GM's both US and EU it appears this was stealth removed with no warning.
Wanted to warn all others that are working toward this item that until a formal response is given I wouldn't get your hopes up.
Maybe if there's enough attention given to this matter a response will be given.
See you in the battlegrounds,