Prot DPS in a raid is quite ok if you wear glass cannon DW gear. Devastate spam adds decent DPS and Executes are better than those from Arms Warriors. It's not good enough for pure DPS races or a pure DPS roll, but that is quite logical.
I got the same result (2nd on damage) with the same spec (8/5/48). I don't think it's a coincidence. First was a fury warrior, maybe Aran just favors warriors. Devastate made up for about 45% of my damage. It is really a huge damage boost for protection spec.