you have to divide from tanks and "dps in tank stance"
this is quite different.
i can assure you that i pvp only rarely in the 50 bracket and because of this i only have the recruit set and with it a tanki can manage to do more than 50k protection, and "some" dps if there is no-one to be shielded by "stance-dancing" to shien.
so if you see focus or vigilance guardian who go soreso for the damage reduction, they are no tank.
if you see a full tank doing 0% protection, that guy have to change class....
my 2 cent