For BGs you can faceroll your way to victory as a retri paladin, yes, but in arenas it's a very different story. It actually takes skill to play it, and, from the top of my mind has only one really viable comp (hunt+ret), with disc/rshaman/mage+ret being viable, but in this meta it would be pretty hard (at significant ratings atleast). Also, RNG is a big factor, it needs alot of constant rebuffing in order to protect your burst with wings etc... I would definetely rate retri pala above DK/warr in terms of skill required for arenas.