Correct me if I'm wrong. But doesn't a tanks dps effect the amount of enmity they can control? The defense stance is a modifier of sorts to increase that. If that's the case wouldn't it be feasible for a really good geared tank to prevent the pull from being taken by a stellar DPS in the middle of the fight? (I'm not sure if Quelling strikes always works because I've seen otherwise) And on top of that the tank is contributing dps (by obvious means).

Although it's fair to say, if dps is lacking, it lies in the dps fault. Not the healer or tanks. I remember seeing this one A.S fight where a tanks DPS was 900, while a whm was 700 SCH 500. VS. a MCH 1600. while the others were 1500-1.2k.