Dude it is pretty much obvious. Ranged classes don't have to run over to you every 12 seconds and lose precious DPS time, while melees had to. Btw nice tactic. My opinion still stands though.
But the dps race on LR-5 isn't that bad. 389,304 health / 180 second enrage timer = 2162 dps for the group. As a healer I keep my DoT on him (100 dps), if tank does about 450 dps, that leaves 800 dps for the melee. Even with the running out and in, that should be easily doable.