Are my mitigation numbers off ?

[Reynhart]

On average your Sheltron increases mitigation by 26% so it's still an excellent skill.

How do you obtain that number ?

If your shield blocks 30% of damage 15% of the time, it means the average mitigation is 4.5%

At most, Sheltron's "effective" duration is 3s (Less on multiple targets, but never more, since it only blocks one hit). It means that it mitigates 30%, of damage, at most, 10% of the overall time (Duration/Recast) for, at most, 3% average mitigation.
On the 90% remaining time, your basic block rate applies., so 90%*4.5% = 4.05%

So, by combining Sheltron and passive Block, you obtain 3%+4.05% = 7,05%.

The benefit of Shletron is not to mitigate a lot more, but mitigate more reliably.

[Freyyy]

How do you obtain that number ?

Because it increases your block rate from 15% to 100% for the hit you want to mitigate.

[CGMidlander]

How do you obtain that number ?

If your shield blocks 30% of damage 15% of the time, it means the average mitigation is 4.5%

At most, Sheltron's "effective" duration is 3s (Less on multiple targets, but never more, since it only blocks one hit). It means that it mitigates 30%, of damage, at most, 10% of the overall time (Duration/Recast) for, at most, 3% average mitigation.
On the 90% remaining time, your basic block rate applies., so 90%*4.5% = 4.05%

So, by combining Sheltron and passive Block, you obtain 3%+4.05% = 7,05%.

The benefit of Shletron is not to mitigate a lot more, but mitigate more reliably.

Using average mitigation is a flawed way of looking at how things work in practice, since the game is largely focused on mitigating (predictable) tank busters. If average mitigation mattered much, then parry wouldn't be regarded as such a crap stat. (Well, it'd still be bad because it scales poorly, but you know what I mean right?)

[Freyyy]

How do you obtain that number ?

If your shield blocks 30% of damage 15% of the time, it means the average mitigation is 4.5%

At most, Sheltron's "effective" duration is 3s (Less on multiple targets, but never more, since it only blocks one hit). It means that it mitigates 30%, of damage, at most, 10% of the overall time (Duration/Recast) for, at most, 3% average mitigation.
On the 90% remaining time, your basic block rate applies., so 90%*4.5% = 4.05%

So, by combining Sheltron and passive Block, you obtain 3%+4.05% = 7,05%.

The benefit of Shletron is not to mitigate a lot more, but mitigate more reliably.

He was speaking about when you toggle Sheltron to mitigate a specific attack. Even if you could also have blocked it WITHOUT Sheltron, using Sheltron still increases your average mitigation FOR THE INCOMING HIT by 26% with a 30% block strength shield in comparison to if you didn't use Sheltron.

Average sustained mitigation doesn't matter in this game.

[Reynhart]

Using average mitigation is a flawed way of looking at how things work in practice

Average sustained mitigation doesn't matter in this game.

Yes, you're right.
There is just a tiny little bit of a problem with this.
PLD most definitive tool is its shield...which provides...average...mitigation.

Not having a shield doesn't prevent you from having mitigation skills so, the fact that Bulwark or Sheltron use it is just cosmetic.

So again, one of the claimed definitive advantage of PLD is, at best, flawed, at least, a blatant lie.

Damn quota....
Answer to below:

Its boost to block rate is significant enough to be reliably useful when pulling a large amount of mobs in dungeons, for example.

Yes, it is.
But dungeons are hardly challenging. And for larger pulls, Bloodbath+Spam-Overpower or Blood Price+Spam-(DA)Abyssal Drain provides far more "mitigation" than Bulwark.
Without talking about the AoE enmity and damage gap...

[CGMidlander]

So again, one of the claimed definitive advantage of PLD is, at best, flawed, at least, a blatant lie.

I can't say I disagree with you on that.

But Bulwark does have its uses outside of boss fights. Its boost to block rate is significant enough to be reliably useful when pulling a large amount of mobs in dungeons, for example.

[CGMidlander]

Answer to below:

Yes, it is.
But dungeons are hardly challenging. And for larger pulls, Bloodbath+Spam-Overpower or Blood Price+Spam-(DA)Abyssal Drain provides far more "mitigation" than Bulwark.
Without talking about the AoE enmity and damage gap...

Aye upon further thought, I'm not sure where I was going with that point. It's probably my mind trailing off.