I think the reason why you might want to exclude vengeance from the discussion is because AoE tanking and doing AoE dps when you have no tanking responsibilities are two very different things, especially on WAR. I'm sure that there is many a WAR who charges into battle, with lofty dreams of pulling all the mobs in Deliverance and spamming Decimate and Overpower into victory. But this is what really happens:
When you go to pull a sizeable pack of mobs out of tank stance and proceed to spend your next three GCDs putting up a Storm's Eye combo, the BLM will probably pull off you somewhere in that 8-9 second interval. Mobs go everywhere. Your healer, desperately trying to heal through the unnecessary damage that you're taking out of stance as well as the extra damage on the BLM, pulls aggro, gets swarmed, and dies. Then, when awareness runs out after 15 seconds, you proceed to take 5 seconds of crits out of tank stance from the mobs during the last few seconds of RI because you forgot to mention to click it off, and you subsequently die just before pacification.
Average Potency/Second = 0.
It was probably the healer's fault, though.
