Are my mitigation numbers off ?

[Reynhart]

A huge thing you are missing on the WAR end is Bloodbath, Bloodbath+Berskerk+maim, Equilibrium+Berserk, and other self healing abilites. Over the duration of a fight the amount of self healing WAR provides is a little obscene. If you look at mitigation as "HP that needs to be healed back" instead of "total damage reduced" the gap widens even more between WAR/DrK and PLD.

Yeah ! More to WAR ! Again...

Yes, you get 16 stacks after 24 GCDs. No, it's not 16 stacks in practice after 24 GCDs (Inner Beast also consumes a GCD). It's actually 8,5 GCDs for 1 Inner Beast on average and Fracture isn't even taken in consideration here.

Yes, it's not really 16 stacks, but you could use one CD for the missing stack every minute. And you can use Inner Beast without breaking your combo, meaning you can probably build one stack immediatly after Inner Beast.
And no, Fracture, is not included since the focus is mitigation. Again, if PLD is supposed to be the best, WAR shouldn't be able to top it, even by sacrificing some DPS.

The problem with calculating mitigation in this manner is that the actual would tend to be widely variant and per situation and fight based. It doesn't take into account player skill or knowledge and views these classes completely in a vacuum which negates natural synergy with other classes and per fight mechanics.

I don't see any reason why a very good WAR would suffer more than a very good PLD or DRK...yet, I see plenty of reasons why a bad WAR would...but we won't make "bad" players the standard.

Also mathematically speaking this assessment falls short for a few other reasons, the first one being user differential in using cool downs (people don't just blow cooldowns because they come available, rather they tend to use them when it is advantageous in mitigating larger amounts of damage or saving them when necessary making the cooldown time assessment unreliable as a mean of mitigation measurement.)

And WAR is probably the one tank that can always have a cooldown ready, if they only focus on mitigation. In the current meta, CD duration is frequently irrelevant, and only recast matters...

It isn't properly accounting for the ultimate cooldowns (which can't be judged within the limited context of these calculations, yet any damage acquired at "1hp" while under the affects of holmgang or living dead is 100% mitigated and depending on the fight this could vary widely with outgoing damage and cooldown usage.)

The problem with Living Dead and Holmgang is that if your HP stays above 1, you basically wasted your CD. That's why I didn't take it into account. But were I to put Hallowed Ground aside too, it would, again, only put PLD even lower.

Last but not least it doesn't account for raid wide mitigation (which would be per fight and is utility) like for instance in final coil, dragon kick (or delirium blade now) was/is one of the highest raid wide mitigation abilities in the game due to the prevalence of magic wide aoe attacks in high level content.

Storm's Path mitigatess at least the same as Dragon Kick/Delirum and Rage Of Halone combined.

Tankbusters Only - This damage should be assumed to be magical most (if not all) of the time.

For that part, there's no need for calculations. PLD loses so much against magical tankbusters that it's not even a competition...which is the actual state of the game, yeaaah...