And the evidence to support that ranking comes from...?

Tanking 5 mans is fine (althought Nature Immune mobs suck), but we just don't have the AC for anything past that. Plus all the annoying things we can do to caster mobs can be done without us in the tanking role. Although I did tank Balinda in AV with only another Shaman and Priest for healing and DPS :D

Shamans are the security guys in front of the crowd during a rock concert (the band are clothes, the warriors are the hells angels crew from Altamont inside the crowd ).

Back in the day on my Shaman I used to get to help tank the Core Hound packs in MC, was pretty fun.

Rockbiter + Earthshock spam + actually healing myself meant that the aggro was all mine. I'm pretty sure I'm right in thinking that Paladins have 50% threat reduction on heals so that they cannot use healing to tank wheras that does not apply to Shamans.

Tanked just about everything pre MC. Shamans have no problem with threat as long as their mana holds out. We can't do shit after that though. With a good priest and a full mana bar I can tank Vanndar no prob.