Tank DPS is the least of your issues.
Considering all these tank dps threads there is something being lost between the lines.
YOUR GROUP IS NOT ELYSIUM OR LUCREZIA!
Does your group put in 18 hours a day spend all that money on draconian pots for every pull in that 18 hour stretch?
What they don't? Sorry tank dps is the least of your worries when it comes to clearing.
Tank dps is a thing but the main point is that the above groups put in so much time and effort that the little switch outs made a difference.
Yes some tanks do a little more then others but it isn't this that's not making you clear. Not everyone can be like the top tier raid groups.
Only posting this here because its mainly the tank community crying about it.
Just let your groups gear progress each week and things will get there. If you want to win like the above groups put in all that time and you will eventually get the results and clears you desire.
I'm going to be flamed for this but I really do get tired of people forgetting something fundamental.