Vlad, on 10 December 2012 - 11:32 PM, said:
I can only think of one thing: someone (probably the current tank) is using taunt on the boss "on cooldown" needlessly, triggering the diminishing returns, and rendering the boss taunt immune by the time your OT wants to take it.
I like Vlad's theory a lot better than mine
If the taunts are truly resisting, then over-taunting resulting in diminishing returns is probably the culprit.
Generally speaking, as a tank, you should really only be taunting in 1 of a few situations:
1 - Boss pull and you want to be sure you keep aggro while building threat. Either use it preemptively or as you see your threat slipping away.
(if you don't have the Threat Plates add-on I would highly recommend it - it colors nameplates based on threat )
2 - You lose aggro during the fight and need to get the boss back (Ideally you should be preemptively taunting in this situation as well, but you cant always prevent it)
3 - Tank swap
Taunt is not a threat generator, it is to make sure the boss stays on you while you gain vengeance and build your threat. Sorry if you know all this already, hopefully someone will gain something from it