I do that in PVE tank gear. It's not fucking rocket science.
Heroics are tuned for tanks with 19-22k health. Tanks at current gear levels have 40-50k health (all unbuffed). Tank weapons at current gear levels do equivalent DPS to what DPS were using back then (and moreso since I take my Bloodvenom Blade out for heroics). Due to massively outgearing, a tank can pull far more, which ramps up his DPS.
This sums up that outdated content is outdated. Congratufuckinglations.