Tank Mitigation vs Tank DPS.

[ReiMakoto]

How is it inherently flawed even with 20% mitigation given all the time?

How are you going to know how tenacity will affect you without these 20% if you dont know how much damage you would take?
Sorry but 4% is still 4%.
Even if you take for example 10k damage, that being reduced to 8k, tenacity will decrease it to 7680, thats still making you 4% more tanky relatively to other tank with only 20% mitigation bonus and without this extra tenacity.
Even if you apply another 20% into the caluclation, making it 6400, if you give one tank tenacity 4% bonus he will still be 4% more tankier and will stand 4% longer relatively to tank without it.

About this healing bonus, its "proven" (no pic, no video, nothing) but the prove is really old, and in game description doesnt detail what kind of HP restored it really affects.

So just dropping into explain, mitigation is multiplicative not additive, so for example in the old system if you had tank stance on as well as using rampart you wouldnt mitigate 40%, youd mitigate 36% (damage ×0.8x0.8) because of how buffs stack. So if in this case tenacity stacks like every other defensive buff, a 4% tenacity would actually equal 3% when taking into account the passive 20% (1x0.8x0.96=0.768) IE youve not been made 4% tankier