Edit after post necroed on Oct 9 19: all of this could be totally wrong.
I want to communicate to new players how big the discrepancy in classes was but I keep getting info that’s absurdly detailed or fanatics for off-specs that claim they can do great DPS if they’re dual-wielding Atiesh on the first full moon of the galactic ecliptic.
Edited: original numbers were too high...still don't know if they're right, but they're closer: There's also an inherent problem in the question (fewer than 1% of players raided Naxx so it wasn't 'normal' to even be in there, and when they were, they tended to have tons of buffs). Also I forgot just how powerful these buffs were, which has made "normal" hard to figure out:
Rallying Cry of the Dragonslayer (Ony or Nef): 10% Spell Crit, 5% melee and ranged crit, 140 attack power (Looks like rogues had about ~350 attack power in pre-raid gear +whatever they had innately)
Spirit of Zandalar: 10% move speed, 15% all stats
Songflower Serenade: 15% stats
Assume very good but not perfect BiS Naxx gear, no legendaries, Rallying Cry of the Dragonslayer but not Zandalar or Songflower. No flask. Assume no Blessing of Salvation or Battle Rez, so have to stay below tank threat.
2nd edit: The numbers below I pulled from an extra-curricular player ranking site so they are certainly achievable, but are still probably the equivalent of modern top parses (possibly with the raid catering to/cheesing for one individual to parse really well). In retrospect I should have specified BiS AQ40 and below gear. Rallying Cry of the Dragonslayer is even more OP than I remember it being, so that also inflates numbers as well. So the numbers for a guild entering Naxx without world buffs or any Naxx gear are probably 200-300 DPS less than the numbers below, putting the averages in the 400-600 range.
850 range:
Fury Warrior
Rogue
Fire Mage
750 range:
Warlock
700:
Hunter
Shadow, Elemental, Feral, Ret, Boomkin: 400-600
All the above numbers could go significantly higher if you start factoring in flasks, legendaries, stacking all the world buffs, and all the other buffs, plus if players could chain Blessing of Salvation or Battle Rez and/or stacking the entire raid so the entire fight lasted a very short time.
OP:
1200 range:
Fury War
Rogue
Fire Mage
1100 range:
Warlock
900-1000:
Hunter
Shadow, Elemental, Feral, Ret, Boomkin: 500-600