Unfortunately, the bigger problem hers is that you guys (the collective you) don't seem to have a good understanding about the nature of tanking, the relative danger, and the importance of DI spread. This is not a new discussion or debate in the tanking community, it has been well hashed out multiple times over the last decade or more. It was this understanding that finally pushed tanks out of the dark ages of chasing hit points, and it is the power of mitigation that forced SoE's hand and started the slow decline in available armor class for PC characters compared to attack values of NPCs. Simply put, being able to do what is shown below in these graphs makes tanking trivial. Trivial enough that tanks don't even need discs, and in these cases trivial enough that having this degree of mitigation will end up comparatively make you a stronger tank than those with far inferior baseline mitigation and a huge repertoire of activated discs and tanking abilities.
I ran a very long string of parses to see just how long it would take for an NPC tank to even take a max hit (DI20). I was wrong in my posts on SoE live - I assumed the furthest right was DI20 but if you count them up it was not. This was a naked pet - no buffs - only the gear it came summoned with at EM15.
>50,000 hits:
Now what does this mean? If we define a dangerous time period as a string of 6 high hits (DI15+).
-Chance for DI15+ round any given hit is about 1.3%.
-Probability of taking 6 such hits in a row is 0.000000000007213% (0.013 ^6)
-Chance is basically 1 in 138,638,569250 (138.6 billion)
-At average rate of hit 4.8 hits per second - this will occur every 8,023,065 hours
Earth pet on trash mob will take a string of DI15+ hits every
915.9 years tanking nonstop 24 hours a day.
If you run the math on Raid geared warrior, you will see this phenomenon approximately every 40 minute. A group geared warrior, every 28.5 minutes. A group geared knight every 20 minutes or less. A monk or a ranger? A lot more frequently.
^ 327 minutes afk so far 26,407 hits (5.5 hours)
Rounds > 30k in 5.5 hours = 8
Max roundin 5.5 hours = 38388 damage
Raid geared warrior with certitude and shield:
30 minutes of fighting
Rounds > 30k in 30 minutes = 6
Max round in 30 minutes = 43k
Group geared shadowknight with certitude and shield:
30 minutes of fighting
Rounds > 30k in 30 minutes = 50
Max round in 30 minutes = 53k
Here you can see how this DI spread plays out in real time - even factoring in the superior avoidance of PC tanks. In 5.5 hours of tanking, the earth pet barely took more rounds > 30k than a raid geared warrior took in 30 minutes. A group geared SK took 50 such rounds in 30 minutes (almost 2 a minute) - whereas the pet takes less than 2 per hour. The max round in 30 minutes for both the raid warrior and group sk was significantly higher than the max round a pet saw over 5.5 hours.
Now the counter argument is that naked afk parsing means nothing. For absolute comparison purposes you are correct, but the baseline is what allows us to then add in known variables. We know exactly how defensive works, how knight discs work, how activated abilities work. We know what stacks and what does not. Knowing the raw baseline damage distribution and avoidance (players beat out pets in this regard), we can extrapolate pretty much anything.
The point is simple, from a tanking standpoint NPC tanks and PC tanks are playing completely different games. From looking at how ac is calculated for NPCs, how much mitigation aa boosts these pets, and how NPCs do not have softcaps with diminished returns - this is the why. In looking at how taking 450 attack away from mobs (basically a raw 450 real ac without any softcap diminishing returns) impacts the DI spread on various tanks - a player tank would need a displayed armor class somewhere far north of 30,000ac (maybe north of 50k ac) to take hits like a pet.
Yes, we all know the limitation of using a pet to tank - they needn't be repeated. Those limitations should be, at best, be the only difference in a dedicated player tank and a pet tank beefed out. In short, in a pet tanking scenario, at best the pet should be no easier to heal than a real tank - preferably it should be a little worse in raw damage intake at baseline with a tank oriented pet being preferable to a ranger or monk. As it stands, in any scenario where a pet is used to tank - from a damage intake and safety to heal standpoint, it actually represents the safest tank out there. For those brief periods where a knight or warrior blows everything, for that brief time period the tank will take less - but averaged over time cycling these abilities - pet wins out. At baseline, there is no comparison.
Now, in the case of knights it gets even trickier. My favorite HA group setup to run with my knights is knight + 5 other dps (one or 2 with some measure of support). This comparison gets tricky as the knight doesn't even need a healer - but neither would the pet need a healer in a ranged group - the owner can provide the requisite healing power for their pet that will be comparable to the knight.
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The goal here is not a nerf call driven by class hatred, it's a request for some measure of balance to be restored. Looking at the variables, it is quite clear that this represents an oversight - a bug of sorts. Any target that is going to function as a tank in a group or raid needs to be on the same playing field. We need to mitigate comparably to each other and avoid comparably to each other. Average dps still favors the pet, but if you look at average dps alone the numbers don't look that bad. My suggestion has been (and I suspect it will actually be taken seriously by those in charge) to bring pet mitigation down to the ranges that player tanks experience while at the same time increasing their avoidance to the same ranges that player tanks experience. There will or would not be a big change in average incoming dps, but the nature of that damage - just like for the player tank - would have those same moments of spike.
You might consider this a nerf, I would consider it a necessary balance.