I know they get amazing around DoDH and beyond, But upon GoD opening next year, or god knows when...how are we on parses until then?
Zerkers when i remembered were actually competent tanks as well as being able to burst on par with a wizard and sustain like a monk/rogue especially with epic.. But with modern changes I would do a test if you have the time to level up a zerker to that era and find gear near pop/god strength.
Zerkers were never good at being tanks, like ever. If a zerker was regularly tanking for you they were either very over geared for the zone or quite a few levels higher than the zone. When Zerkers first come out on the TLP servers they will be around Rogue level dps, maybe a little below depending on what all AAs they have access to initially, since some of their balance was achieved via AAs. They will be a solid 2nd of the melee dps hierarchy; after DoDh they will start rivaling Rogues.
