<edited it to make it short and sweet>
ok first off this is not a thread to QQ or to flame, but i was wondering.
If u had a warrior/pally/druid/dk all with the same avoidance <miss/parry/dodge> placed against a mob, would a warrior/pally survive longer since they have shield block against a druid/dk without any tanks using active tank cds?
Block gives a chance to take a fixed amount of damage off a melee attack.
Not sure about the rest of your post, please reformat it to make it more readable.
It's hard comparing tanks. because they would never have the same avoidance stats.
Druids can't parry.
So if the Warrior/Death Knight/Druid/Paladin
All had 5% miss.
and the paladin and warrior had 10% block with a blockvalue of 500.
A mob hitting for 1000 damage each second would be better mitigated by Warrior/Paladin.
It is very simple.
There's a good thread on the EU forums about this where the OP runs simulations to find the answer to that question: World of Warcraft (en) Forums -> Pre 3.1 Exhaustive tank comparisons.
From his data, the answer seems to be no. Druids have a significant advantage in TTL (time to live) from larger health pools, and take less damage per second because of higher armor. DKs take by far the least damage per second because of the talented (no DR) avoidance, but have comparable TTL to war/pal.
His simulations use the live mechanics, not ptr.
That's the truth of it, for the time being each class has it's strengths and weaknesses. Live DKs have heavy avoidance and slightly higher armor, Warriors/Pallies have block and passive protections but the lowest avoidance, and Bears have slightly higher avoidance and big big armor with high health.
I'm not sure of how the current state of the PTR is really working, I haven't tested it well. But they seem to be stripping away a lot of DK avoidance so that margin seems to be narrowing a lot.