You're thinking too old school. The way prot warriors work now is that they take less damage and have higher effective Shield Block or Shield Barrier (used interchangeably depending on boss mechanics) uptimes based on their rage generators, which are shield slam and revenge. Now... getting more parries/dodges does allow you to hit revenge more, and mastery gives you a a chance to get 10 rage on a block.... but the problem is that all of those are worthless if your hits aren't landing.
The way the rage gen calcs work out, if you're hit capped to 7.5% and EXP capped to 15%, then you're pretty much guaranteed to have enough rage to keep the maximum uptime on shield block, which is really what you're going for.
Now, if it's a boss mechanic where there's a lot of magic damage, then hit/exp become even more important because it's pretty much the only way to keep sbar up as much as possible. After that, go stam.
Mastery becomes pretty devalued as a prot warrior since if you need to be blocking something you probably have sblock up anyways, and more crit block helps but.... it's really not that big of a difference compared to missing a shield slam when you need it. You want to be sure to have your active mitigation up as much as possible in order to smooth the damage intake. Steady damage intake has never killed a tank unless his/her healers had already died. It's the spiky stuff that kills tanks, that's why you don't really worry about how much parry/dodge you have. You take what you can get from gear, but in general, this is the stat priority:
hit/exp >> stam = mastery (depending on fight mechanics) > dodge/parry
Honestly, I kinda like going the stam right just because boss fights right now have soooo much magic/unblockable damage that it really helps to have a big EHP pool.
Hope this helps, let us know if there's something else you need clarified.