Quote Originally Posted by Mercbeast View Post
You have to remember that this is basically peak shadowpriest for pvp.
True, shadow priests are good duelists but they have less mitigation, less health and fewer defensive cooldowns than warlocks. Warlocks also have either 2 or 3 instant DoT's as well as a instant ranged slow (depending on spec.)

However, aside from all that, the biggest issue with shadow priests is their mana. SW:P costs 500 mana to cast. If you're running around spamming it in a large fight you'll be OOM quickly. Warlocks with a healer support can spam their DoT's all day.