Prot warrior Critical block mechanics: Help me clarify!

I'll apologize right off the bat for my explanation that's doomed to be a bit cumbersome.

As I'm understanding things, our chance to critically block an attack is based on a percentage of our chance to block the attack. So, with a base 8% chance to block an attack, and a base 8% chance to critically block the attack, that would mean we have an 8% chance to block 60% of the damage when we block, or a 0.64% chance to critically block in general. Please correct me if I'm wrong on that, because all of the following assumes the above...

Anyways, as our chance to block goes up, our chance to critically block *when we're blocking* also goes up. The implications here are rather interesting, because it means that our mastery has cumulative returns when it comes to critical block. On top of that, we get to a point where each point of mastery actually gives us more critical block chance than block chance.

10% - 1%

20% - 4%

30% - 9%

40% - 16%

50% - 25%

60% - 36%

At a 10% chance to block, we have 1% chance to critically block... 20% chance, 4% crit... etc... From 50% to 60%, our chance to block increases by 10%, but our chance to critically block increases by 11%. This means that even if we're unhittable, mastery remains a fantastic stat for melee damage mitigation.

With that in mind, I'm curious how critical block fits into the avoidance table. Is there a second calculation when we block to determine if it's a critical block? Or does critical block chance push block off the table? If it's the latter, then mastery is slightly better than if it's the former, as becoming critically block capped is much more viable, theoretically.

edit:

Made a mistake.. Base mastery is 8. Base block chance would then be 12%. **Looking at my chance to block, it also seems that the way I was thinking critical block chance was calculated was wrong. I had assumed that 3% overall chance to block was just too much, compared to the paladin's 2.25%, especially when half of that 3% goes to doubling the amount of damage mitigated.**

**edit again:**

**Concerning the bolded part, turns out this is incorrect and I was correct in my original assumption.**

WoW this is a great Discussion

Thanks for all info. folks,,,,,i really had no idea how the block mech. actually worked. I LOVE reading these informative post. This is why i LOVE tankspot.