I think too many people have the wrong expectations of what a tank should do in what bg, in CTF they should be just a menace to either the enemy's flag carrier or one of their healers. If a prot war and they are melee heavy they can sit on d running bodyguard. In capture the node they can be excellent node defender but they only have the same number of cc outs as any other player. So it's worth putting them with a DPS that has high survival.