Thanks for preserving this, it's full of very valuable basic tanking information, and anyone who has not tanked before or isn't yet a big theory buff should really know this stuff.
Aside from some nit-picky word fixes (Blade Barrier is avoidance not mitigation), I have a couple short corrections/adjustments:
1.) I always value expertise over hit rating, even after removing dodges from the table. Removing Parry chance is a survivability issue, not just a threat issue (I'm sure you can find more discussion on this in the forum archives).
2.) The parry rating gained from Strength is not subject to diminishing returns, the total parry rating is though. Strength adds parry rating, not %, but the point stands, in all cases take strength before pure AP gear for tanking (this will really just be a guideline for weapon choice once you have tank gear).
3.) 1 Parry rating != 1 Dodge rating in value at any point. Diminishing returns works such that every increment will be as valuable as the last in raw survival value (though it'll give you decreasing amounts of %). The forumla uses a "cap" as the limiter to an avoidance stat for the calculation. For a DK that is 47% parry, 88% dodge. You get parry % from parry rating (fed through Str, but only the rating is diminished) and defense rating. You get dodge % from raw Agility, dodge rating, and defense rating. I'm working on a general guideline now, but suffice to say equivalent ratings will not likely end up the same. But again the general point is a good one, if you have high agility and high dodge rating and low parry rating, say 50 parry rating will be worth more avoidance than 50 dodge rating, but you can't base the comparison on direct rating comparisons.
Things to take home, themes from his post:
1.) You have to survive as a tank, first, burning up threat and dps comes second to that. A dead tank is saving no one if you can't survive the people you're holding on you. DPS can slow down if you can't go full tilt on threat, but they can't resurrect you if you get torn apart.
2.) Welcome to the new world order, exemplified in the DK talent tree construction. There is not ONE way to do it. Be smart with your talents, don't just follow what someone else tells you. Test them, try them out, shift your specs until you find the one that works best for you, and match your rotation and play style to match your spec.
3.) The most essential non-technical aspect of tanking is also one of the most overlooked in sub-par tanks. Spatial Awarness! You need to know where things are, where they're going, and when. Is something CC'd? How long until it comes loose? Did one of your mobs break loose and head for a healer? Did the hunter just back up and accidentally body pull another group? If you are always keeping your eyes open for these things, people will notice the difference and thank you for it.