Direct me to said math on critical block you're referencing and I'll be happy to point out its flaws. I'll also just go through my own math on the subject with various scenarios past full CTC where avoidance is superior to crit block.

I'm assuming ratings after all buffs, fighting a boss that averages 5 swings inside 10 seconds for HTL uptime, 33.333..% SB uptime, and using the 1% BV meta:

Ratings: Mastery = 4100, Dodge = 2000, Parry = 2400
HTL Uptime = 1-(1-.1608)^5 = 58.37%
Base CT: Miss = 4.4%, Dodge = 14.43%, Parry = 16.08%, Block = 65.09%, Hit = 0%
Crit block %s: Normal = 46.3%, with SB up = 74.32%, with HTL up = 56.3%, with HTL+SB = 84.32%
Average dmg taken after avoidance: Normal = .6509*(1-.463)*.69 + .6509*.463*.38 = 35.57%, with SB up = .6509*(1-.7432)*.69 + .6509*.7432*.38 = 29.92%, with HTL up = .6509*(1-.563)*.69 + .6509*.563*.38 = 33.55%, with HTL+SB = .6509*(1-.8432)*.69 + .6509*.8432*.38 = 27.9%
Average uptimes of each situation: Normal = (1-.5837)*2/3 = 27.75%, with SB = (1-.5837)*1/3 = 13.88%, with HTL = .5837*2/3 = 38.91%, with HTL+SB = .5837*1/3 = 19.46%
Total average damage taken = .3557*.2775 + .2992*.1388 + .3355*.3891 + .279*.1946 = 32.508%.

Skipping some of the more verbose math now, but it follows as above.
Adding 100 dodge rating to Mastery = 4100, Dodge = 2100, Parry = 2400:
HTL Uptime = 1-(1-.1608)^5 = 58.37%
Base CT: Miss = 4.4%, Dodge = 14.85%, Parry = 16.08%, Block = 64.67%, Hit = 0%
Crit block %s: Normal = 46.3%, with SB up = 74.74%, with HTL up = 56.3%, with HTL+SB = 84.74%
Average dmg taken after avoidance: Normal = 35.34%, with SB up = 29.64%, with HTL up = 33.34%, with HTL+SB = 27.63%
Average uptimes of each situation: Normal = 27.75%, with SB = 13.88%, with HTL = 38.91%, with HTL+SB = 19.46%
Total average damage taken = 32.270%

Adding 100 parry rating to Mastery = 4100, Dodge = 2000, Parry = 2500:
HTL Uptime = 1-(1-.1648)^5 = 59.35%
Base CT: Miss = 4.4%, Dodge = 14.43%, Parry = 16.48%, Block = 64.7%, Hit = 0%
Crit block %s: Normal = 46.3%, with SB up = 74.71%, with HTL up = 56.3%, with HTL+SB = 84.71%
Average dmg taken after avoidance: Normal = 35.35%, with SB up = 29.66%, with HTL up = 33.35%, with HTL+SB = 27.65%
Average uptimes of each situation: Normal = 27.1%, with SB = 13.55%, with HTL = 39.57%, with HTL+SB = 19.78%
Total average damage taken = 32.264%

Adding 100 mastery rating to Mastery = 4200, Dodge = 2000, Parry = 2400:
HTL Uptime = 1-(1-.1608)^5 = 58.37%
Base CT: Miss = 4.4%, Dodge = 14.43%, Parry = 16.08%, Block = 65.09%, Hit = 0%
Crit block %s: Normal = 47.14%, with SB up = 75.99%, with HTL up = 57.14%, with HTL+SB = 85.99%
Average dmg taken after avoidance: Normal = 35.4%, with SB up = 29.58%, with HTL up = 33.38%, with HTL+SB = 27.56%
Average uptimes of each situation: Normal = 27.75%, with SB = 13.88%, with HTL = 38.91%, with HTL+SB = 19.46%
Total average damage taken = 32.283%

Adding mastery yields the worst gain in damage reduction. Now I'll skip all the documentation of the math since doing it is the same and just list the gains at other hypothetical gear situations:

Starting with Mastery = 4900, Dodge = 2000, Parry = 2400:
Dmg taken = 30.707%, +100 dodge = 30.48%, +100 parry = 30.474%, +100 mastery = 30.482%

Starting with Mastery = 4100, Dodge = 2350, Parry = 2850:
Dmt taken = 30.632%, +100 dodge = 30.408%, +100 parry = 30.408%, +100 mastery = 30.417%

To illustrate how DRs really don't have an impact, starting with 5200 dodge, 5500 parry, and only 2000 mastery:
Dmg taken = 23.993%, +100 dodge = 23.832%, +100 parry = 23.833%, +100 mastery = 23.841%

I could never find a scenario where mastery would ever be preferable to dodge or parry, so long as your dodge and parry are kept relatively close. If they're not close, mastery can overtake whichever one you have too much rating in, while the other will end up even farther ahead. I opted to leave out a really high mastery situation(past 5000 or so), since mastery diminishes in value again as soon as your crit block is capped with SB+HTL, which vaults dodge/parry well above it.

The ideal breakdown of avoidance stats once you're able to cover the combat table and given a fixed avoidance stat total to distribute will always be: As much into Dodge/Parry as you can get, splitting the 2 near evenly, with a bit of extra parry rating for HTL, while still having enough mastery to just barely cover the rest of the table.

This may no longer be correct. It depends entirely on which Shield Block crit bonus formula is used in-game.

The results in thw quoted part were obtained with a formula where it's no possible to get more than 25% crit block from Shield Block. However older testing has shown this to be possible. So the question is which formula is actually used in the game now.

^^ You need to link said spreadsheet when saying stuff like this.

I can assure you I understand the two roll nature of Critical Block perfectly, though I'm not entirely sure you do.

Did you calculate armor in there as well?

Anyway, there's some posts about this in the Prot Warrior thread since the start of Cataclysm that go into further detail I think, but the one linked recently to the WoW boards has some pretty decent math in it: Hold the Line 2: A guide to warrior avoidance - Forums - World of Warcraft

I know this graph doesn't include dodge, but ultimately it would just flatten out a bit. It's a pretty good visual for what Mastery stacking does.

The two 346 trinkets blue trinkets mentioned were OP for Prot Warriors. For physical damage, on average. pre-Firleands they were better than most higher level trinkets. The Crab especially so. An average mastery of up to 456 ((1710 X 20/100)+114) reforged, plus 171 dodge is just a bit shy of 5% coverage. The Finger lacks mastery and has less average coverage, but is a solid 2nd trinket. The weaknesses of these 2 trinkets is that part about 'average'. Towards the end of the Shannox and Beth'tilac fights, you may want more on demand and less on average.

No, actually. Taking into account every aspect of both weapons, it would be better for you to hold onto Sulfuras, the Extinguished Hand until you can pick up the Heroic version of that item. The potential Strength bonuses from Sulfuras more than make up for the difference in weapon damage (at 545 Strength, Sulfuras actually offers a 24.75 DPS increase over Skullstealer Greataxe). Further, Haste is horrible for Warriors- you're better off sticking with the Crit and lower Mastery rating (since you'll likely be reforging out of the Mastery anyway).

Skullstealer is slightly better, although both are very close, you cannot use the potential of 2 JC gems as you would be using those anywhere in your gear lowering the str gain to 31pts which the dps/dmg of skullstealer outperforms. I did not double check this math but after reforges you are looking at :
170 crit and 31 str vs 70 mastery, 187 haste and 33 weapon damage.

This is all mainhand in my theories though as I believe sulfuras would be the better offhand as its more of a statstick there.

Even assuming we are using non-JC-only gems (+40 Str), Sulfuras still offers more desirable stats and a 17.04 DPS increase over the Skullstealer. But I should, also, clarify that all of my math is based on the weapons being Main Hand-equipped.

I actually found my mistake- I was simming based on the Human bonus to Exp using Maces, and I did not actually reforge away from Haste. After correcting my mistake, it turns out your math is correct. Until we have access to H Sulfuras, H Skullstealer is the better main hand option.

B.
It's a two-roll system. One roll on your initial combat table to determine if it's a block at all, then a second roll to determine if it was a critical block.

It's without SB.

Block capping is extremely difficult for warriors. Unless you're in mostly 391s, you won't get there.

It's a goal, not a must-have.