Does anyone know how to read here, I've grouped with blood tanks doing 10-11k DPS, it has nothing to do with who knows the class better. It is clear Whoda doesn't know how to play a blood tank given that fact.
Gear, latency/framerate, party composition, and location/situation, etc, can all factor in to DPS.
Also, in terms of WotLK, DPS was abnormally high towards the end due to the way gear was optimized. The hit cap remained the same throughout the expansion and yet every tier offered more and more hit rating per item. This meant that in the upper tiers you could get less hit rating and a lot more crit/haste.
As an example, I'm a balance druid. I was in a heroic group with a balance druid. His gear was better than mine, not substantially but still better. I also was having some latency issues that night and because of this I had to adjust my timing for chain casting, which I screwed up once in a while. This caused my DPS to be about 2-3k less than his on most pulls.