BM hunter representation in 3v3: 2.8%
BM hunter representation in RBGs: 0.9%
Blizzard's response:
Beast Mastery Agility reduced by 10% in PvP.
Developers’ Notes: We’ve found Beast Mastery damage to be too high, but we don’t feel that it’s due to any specific ability or mechanic, so we’re reducing the overall PvP template.