Where can I lear about the math behind mechanics?

Hey everyone, I am looking for where I can learn about the math and mechanics about tanking/wow on a warrior. I've read some stuff on EJ but confused where they are getting the numbers from.

I attempted to try to find the % of damage taken and added in the mitigation from defensive stance and armor, but then got confused how to calculate block added since there is a % chance to block/crit block and then the amount block is 30%. Also adding dodge into the equation threw me off because I wasn't sure if it was based on a roll systems where a dodge/block occurred at the same time, the dodge would be used.

Other things I am interested in finding is effective health of myself, and the actual damage by a boss (as opposed to the perceived damage we see on the screen).

I remember that Tankspot, a long time ago, used to have a separate category with all the math and theory crafting, and I am basically looking for another resource like that.

I have seen calculators for TBC, WotLK, and even some Cata, but those seem outdated. Like TBC calculates the haste bosses used to get after they parried one of your attacks.

Anyways if someone could direct me to a place where I can learn some of this stuff and understand it better that would be awesome.

Thanks