I assumed 1400 average inner beast (this is averaging crit and non-crit, assuming Maim / Storm's Eye is up every time), 7000 WAR HP, 770 incoming DPS, ~100 tank DPS. I also assumed 100% physical, blockbable damage (Basically, Caduceus fight). I also assumed 26% block value as that seems to be standard for Holy Shield +1 PLD's. Finally, I left off Awareness because I don't know if I am safe assuming bosses have a crit rate of 10% and even if they do, they certainly don't crit on specials like Rock Buster / Mountain Buster / hood swipe, etc. I also counted Foresight slightly higher at 10% but that isn't really enough to matter. For this I'll use 7.5%. Also, I counted Berserk as a defensive cooldown (though I left off Internal Release as it seems slightly speculative). Finally, I didn't count Second Wind because I think it's a bad cooldown, personally.
For Convalescence, I took the amount of damage needing to be mitigated and considered that roughly the amount of healing needed, then I looked at the difference between healing required before and after.
So if a boss is doing 770 DPS, that's low enough that a WAR should be using Inner Beast whenever possible unless they are saving it for spike damage. Again, assuming a fight like Caduceus most of the damage is predictable. For this reason, I treated Infuriate as it is: a 7% increase in healing recieved for 20 seconds on a 60 second CD. And using Inner Beast every 20 seconds is essentially a net heals per second of 70, which reduces the damage to be mitigated to roughly 700 (not exact when it comes to foresight, but close enough). Also, for this reason I am clearly counting the Defiance bonus as 8%, due to that being roughly the average assuming you use Inner Beast every 20 seconds and only use it after you've used Heavy Swing.
Using my numbers:
Foresight .075 * 20 * 700 / 90 = ~11.7 DPS mitigated
Featherfoot .15 * 15 * 700 / 90 = ~17.5 DPS mitigated
Bloodbath @100 DPS 100 * .25 * 30 /90 = ~8.3 DPS mitigated
Thrill of Battle 1400 / 120 = ~11.7 DPS mitigated
Convalescence - base HPS required = 648, HPS required during convolescence 546. Difference = 102 HPS. 102 * 20 / 120 = ~17 DPS mitigated
Infuriate - Since I'm counting using Inner Beast every time it's up, essentially, it works out to ~8% healing increase for 20 seconds on a 60 second CD. Base is the same as w/ Convo. With IB it's 608 HPS required, a difference of 40. 40 * 20 / 60 = ~13.3 DPS mitigated.
Berserk = Increase Inner Beast damage to roughly 2k averaged. a difference of ~600. 600 / 90 = ~6.7 DPS mitigated (potentially double if you Double IB during a Berserk).
This totals ~86.2 DPS mitigated for WAR, or about 12% of the incoming damage.
For PLD 770 DPS is cut to 616 incoming damage via Shield Oath (though I am still assuming that Rampart / Sentinel are additive, so their reduction is based off of 770 not 616).
Foresight .075*20*616/120 = ~7.7 DPS mitigated
Rampart .2*20*770/90 = 34.2 DPS mitigated
Sentinel .4*10*770/180 = 17.1 DPS mitigated
Bulwark .6*.26*15*616/180 = 8 DPS mitigated
Bloodbath @100 DPS 100*.25*15/90 = 4.16 DPS mitigated
Convalescence - Base HP/S required = 616 after Conva 456, a difference of 160. 160 * 20 /120 = 26.7 DPS mitigated
Hallowed Ground* 616 * 10 / 480 = ~13 DPS mitigated
* I don't like to count hallowed ground because just counting how much DPS it mitigates trivializes its usage. It is much better than that, and I consider it a factor but I don't like counting it as a traditional mitigation cooldown. It looks like one of PLD's worst cooldowns if examined in this light, but it's clearly their best. But I added it here for kicks.
This leaves PLD with a total of 110.9 DPS mitigation. Though in fairness this is significantly higher due to the incoming damage of PLD only being 616, it's effectively 18% of incoming DPS mitigated. I personally leave off Hallowed Ground though, which drops it to ~98 DPS mitigated, which is much closer to WAR's 86.2, and ends up being ~16% incoming DPS mitigation.
So I suppose you are right. Even using my numbers, methodology, and preferences, PLD's have ~30-50% advantage in terms of mitigation from cooldowns. I guess I was selling PLD cooldowns short by saying there was a parity. And it is worth conceding the point that getting all of that out of your cooldowns is going to be between difficult and impossible for practical terms, because it means never getting an ounce of overhealing on WAR, along with a near perfect rotation, which is unlikely.
I still stand by my assertion that the passive mitigation is a bigger deficit, though. And the fact is that Shield Oath begins to outperform Inner Beast/Defiance at incoming DPS levels ~400.