A jugg as a tank is the most overpowered class/spec in the game. No, the OP king is not the bubble sorc, and no, it's not a smasher (neither is really OP, just needs some tweaks). It's a tank jugg. No team has any success without a juggernaut tank. PT tank is a total LOL in PvP, and tanksins have different priorities than actual tanking.
So go ahead, and move away from the most overpowered spec in the game.
So according to your logic, a Juggernaut or Guardian is OP because they are the best at tanking ?
Being the best in something doesn't necessary mean it's OP, it can also mean that all other are weak and underpowered.
As a former tank specced Shadow, here what I think : the only tanky person I ever faced was a Guardian and I think that what all the tanks should be when using proper tank build and gear-. As a Shadow I think I'm underpowered as a tank, but OP if I use DPS gear while in tank spec because of some talents that haven't been well thought.
So a tank Juggernaut is OP ? I really don't think so.