You don't need it to be crit proof if you are at 102.4% avoidance, but the talent is still mandatory for the 10% DR and as a prereq for other mandatory talents.

You're talking two completely different things. Block capped does not mean that you will never be crit, it means you will never have a melee hit that isn't a Block, Dodge, or Parry. Crit capped through Sanctuary means that you will never ever have a critical, crushing, etc. hit. If you are Blocked Capped and not Crit Capped, the Crit will be mitigated, but you'll still be crit. Your healers will hate you.

and then there is the possibility of getting hit in the back, it shouldn't happen much but it can and then your avoidance is shot.

@KrazyKorean728

That's incorrect. You are describing a 2 roll system (one roll to determine crit, then another to determine block) when in reality it is a one roll system. If you push regular hits off of the table you also push critical hits off of the table (the game will only see it as a blocked hit, never a critical hit that was also blocked). The risk of not taking the crit talent would be, as Josh pointed out, a hit in the back if you were mispositioned could be a crit since you would not be able to block/parry/dodge said hit....

The only time it uses 2 rolls as far as i know is for the warrior mastery, one to determine if it's a miss/dodge/parry/block/hit and then another if that hit is blocked to determine if it's a crit block.

Grom

@Grom

You've missed the point of what I was saying. I was not saying it was a two system roll, but rather Crit Cap & Block Cap are not the same thing. The 102.4% CtC assumes that you are Crit Capped through Sanctuary. CtC pushes "regular" hits off the table. Sanctuary pushes "critical" hits off the table.

http://us.battle.net/wow/en/forum/topic/2489160859

"The attack table is filled out in that order, from top to bottom. Now, criticals are kept in for the sake of completion here (I've left out a few things that tanks need never worry about, such as glancing or crushing blows) but against bosses, the critical chance is always 0% provided you've specced correctly. There are mobs, however, who can crit despite having those talents but that's not going to be covered in this thread.
It's worth noting here that player attacks use the same sort of attack table (I'll touch on this later)"

If you're block capped, you're crit immune. Every hit will be a dodge, parry, miss, or block. There is no room for crits to occur. This is no longer something that's relevant, since you'd be insane to pass the crit immunity talent, but in previous expansions it was very possible for a protection paladin to get critical strike immunity while being under the minimum in defense.

@ KrazyKorean728

You are mistaken. From your own link, you can see that the last two entries on the combat table are crit and hit. If you accumulate enough dodge, parry, miss, and block to reach 102.4%, you push both crit and hit off of the table, making yourself uncrittable.