Mastery for DK PvP?

[Mashiro]

Hi Guys,
fuck me if im wrong, but i used the search and found nothing, so -
is mastery a desired stat for PvP (Arena / Rated BG)?
If yes, for which Spec it is better?
and as a last question, whitch mates are the best for 3v3 / 2v2 ?
Thanks for the answers

[Emothianes]

Mastery is valuable for Frost and worthless for Unholy, this is true for 2v2, 3v3, 5v5, Rated BGs, 5mans, and any raiding situation. Though it is worth mentioning that DW benefits more from mastery than 2h by a respectable margin.

[Sygnantus]

i'm trying to max haste and have mastery as second stat since reforge into crit won't raise the crit that alot to be noticed, and 70% of on disease is not that bad consider that if you apply them after a fallen crusade plus trinkets they least at full power for 30seconds.