I'm sure pvp increases your stats if you are under 50. Perhaps, it overcharges your armor rating so much that it does nothing (unless you are vet rank). I don't know, though. (edit meant vet rank not tank)
Bound armor significantly increases my armor rating in PvE. In PvP, it does not increase it even 1 point. My armor rating is the same or very nearly the same in PvP as in PvE.
The character is Lvl47 and does not appear to receive a significant boost in stats in PvP. The armor rating in PvP without buffs is many hundreds below the armor rating in PvE w/bound armor.