It's not just OP. It's a low gear requirement class that absolutely thrives in small pvp. You don't need lots of gear to win as a DR when you can stun lock your opponent, and deal huge crits with your skills while being able to teleport and run away. It's an absolutely gearless and brainless class that really only needs 7 or 8 active skills, which is probably why it's so heavily favored.
It's koo tho, as people gear up the DRs become memes.