A1S isn't a particularly good measure of DPS.
- Is your group killing it fast enough to avoid a jump? (0 dmg for whatever time drops it hugely)
- Are you MT or OT before the split?
- Are you counting Faust or not?
- Are your healers letting you drop out of tank stance? .. How often?
All of these things change the number considerably.

If you want a good measure, try a dummy or just Faust. Even A2S is a little better because there's really no downtime.