Well, 365 agi is worth 2018.45 to AMR, whereas 394 PvP Power is worth 2127.6.
And also, remember that PvP gear has (effectively) 4 secondary stats to 2 on PvE gear. Blizzard said that they don't want PvE gear in PvP and the PvP Power change did exactly that.
Like I said, Resilience is king on top of all this...