I have a question on a subject that I have tried to research and can find no answers as of yet!
Last night in Naxx 25 we were on Thaddius and all was going well, whilst on the boss fight our MT was carrying out his role and all was fine I was one of the 3 tanks in the raid and at the time and during the evening I had my vigilance on one of the warlocks who at times pushes out 2.8 3k dps and around 6k tps at times even more on this encounter. Whilst we were fighting the boss on the polarity shifts I was doing around 3-5k tps when very quickly in a matter of seconds my TPS jumped to 9k then 11k then stabled out this overtook the MT who in the split seconds I thought had died. Due to my sudden massive threat jump so I commenced to tank solid. I then noticed him on the threat meter and stopped my rotations to lket him get back up this was ver difficult to drop and I backed off completely to do this all I can say it was a weird experience.
I have one or two theorys.
1. Vigilance on the lock may have cused this due to the increase in his dps from the polaritys tus transfering threat to me he could have had massive crits 2-3 in a row.
2. I didnt have to shift for up to 2 times on the polarity shift as it didnt change for me thuse my sustained tps didnt drop.
3. My rotation may have caused a large dps spike.
Tried to look in my combat log but couldnt find too much and after raid we had a discussion and we were asked if we had taunted the boss this definately did not happen I can though understand how that could be concieved but taunt was not used, the other tank also was having over aggro problems in raid last night also could vigilance be the problem I think it could. If any one has any answers or similar behaviour it would be interestring to discuss.
I have absolutly no problem to keep my tps above 10k on Thaddius, with Shieldblock and some crit luck it goes up to 17-19k so his tps was really poor if you was able to get Thaddies aggro in few sec getting 9k tps only...
Vigilance dont boost your threat from 3-11k threat. Most likely you had some lucky crits etc. Disregarding that it sounds like the mt had poor threat i would recomend you to stay further behind while "ot". You should never be able to overtake the mt in split seconds as you say, atleast not on fights like Thaddius.