A little while ago, Drysc said in a post that "a prot warrior or shadow priest or what have you should though be able to jump into a battleground or arena and be able to do something with some small amount of success." This hasn't gone over well with many shadow priests. Even with Drysc trying to correct himself in multiple threads and insist that he doesn't mean that the class will never get more viable, a lot of shadow priests are up in arms.
It's probably pretty understandable. After all, before Burning Crusade, a Shadow Priest was pretty much universally feared upon the field of battle. They seemed to take almost no damage in Shadowform, and their DoTs tore through you with ease. Even in the early days of the Arenas, you saw quite a few Warlock/Shadow Priest teams tearing up the charts. These days, Shadowform doesn't really absorb damage like it used to, Psychic Scream doesn't really cut it as CC, and resilience makes sure that their DoTs are blunted quite handily. So what DO you do when you chose a class and spec to PvP, only to have that spec suddenly become lackluster in PvP? This isn't like Protection Warriors, who have known from the start they'd be good as tanks, and tanks alone.
We all generally have a good idea these days of what we roll a class and choose a spec to do. A Protection Paladin expects to tank. A Mage expects to DPS. But it's the divide between which specs are good at PvE and which at PvP that seems to be getting a little thorny lately. Should a player be able to count on their spec always being viable at the same aspects of the game? If so, should Shadow Priests expect PvP buffs sooner rather than later? Or should they accept that their age of PvP dominance was in the Battlegrounds and the pre-70 era, and resign themselves to speccing Discipline if they want to succeed in Arenas?