Resto Shaman Stats Question

[Eeshen]

From what I've seen from the Resto guide, I want Vers then Mastery.
However, from a PvE standpoint, it is Crit then Vers. What gives Mastery edge over Crit in PvP versus PvE?
Main reason Im wondering is in RBGs, I oom fast. Was considering switching Mastery to more Crit.

[Zenzy]

Crit's effectiveness is nerfed in pvp by 50% iirc. Meaning stacking crit is a really bad idea unless your whole class revolves around it like fury warrior or holy paladin.

Mastery for shaman increases your healing based on how low the target of that heal is. Meaning you dont have to cast as often because your heals are more effective on lower hp targets.

What i mean by this is if you cast a healing wave on someone who's 95% hp it will top them yes. but if you wait a few seconds for him to be 85% for example. it will still top him and you'll essentially be saving more mana!

I hope im making sense with this example.

As for RBGS I'm not entirely sure. But the same problem comes with crit being nerfed in pvp. Also from what i remember about rbg's and resto shamans most of your healing comes from healing rain with the talent to dispel. I know this is based on crit yes. however reducing your overall healing via replacing mastery gear with crit gear doesnt sound like a good idea.

I'm probably making no sense. so feel free to reply and see if i helped you at all