This set of tier gear is very annoying if you're trying to min/max gear. Three of the 5 pieces are Crit/mastery, making them the default worst 3. Unfortunately the two that don't are shoulders and pants, which drop off the 12th and 13th bosses respectively, and shoulders are a lower budget slot than helm/chest/legs. So picking up the 2p is more of a combination of what you have available to you and how little mastery you have to force yourself to deal with.
Helm - Immerseus helm is perfect and early, way earlier than heroic tier helm. You can pretty safely say that helm is NOT a piece you want to use for tier.
Chest - Norushen chest has haste instead of mastery from the tier chest (which drops off Sha and is also very early), but it has yellow and blue sockets which aren't ideal. It's not a bad choice for a tier piece but I got lucky and got a heroic warforged chest off Norushen so I run with that.
Gloves - Low budget slot, as such what exactly you use isn't a big deal. Norushen gloves have hit and a blue socket (ew, 700+ forced hit) While Galakras gloves have mastery and a yellow socket on them (again, non-red sockets aren't very good). Meanwhile tier gloves have double red sockets and mastery, making them technically slightly worse than the Norushen ones if you could actually handle that much hit. The alternatives not being good and being a low budget slot makes tier gloves the MOST IDEAL mastery tier piece to have to wear if you really need to (you'll find most heroic WWs wearing them).
Shoulders - Low budget again, tier is better itemized than the two alternatives (which both have non-red sockets and mastery), but there's that annoying issue that the third to last boss in the entire expansion drops them. Normal tier shoulders isn't a bad idea for 2p because the alternatives suck even if they are heroic, but still not necessarily ideal because...
Legs - Tier pants are perfectly itemized except for yellow sockets, but no hit/expertise/mastery to deal with here. What's more is that the alternative is awful, double blue sockets and mastery. I'd go with the shitty Dark Shaman pants if you manage to get a warforged one, but if not heroic gloves + normal legs would be the best setup.
So possible setups are, from best to worst:
Heroic legs + heroic gloves
Heroic legs + heroic shoulders
Heroic shoulders + heroic gloves
Normal legs + heroic gloves
Normal shoulders + heroic gloves
Anything involving chest/helm.
This is all assuming you have access to the best off pieces. There's no reason to be missing normal shoulders or legs if you really need them because normal Siege + Paragons + Garrosh should basically be disenchant and random off specs by this point. Of course don't switch out if you don't have a suitable off piece, i.e. if you don't actually have a heroic chest off piece you wouldn't drop your tier chest.
*Above copied from
http://www.mmo-champion.com/threads/...9#post24098429 because I didn't really feel like typing all that out again.