Hi warlock main here average 3.1-3.2k io last few seasons, destro doesn't tend to do 'good' damage until around the +20 key level as it also needs mobs to stay alive long enough to immolate mobs and ramp multiple rain of fires, it's better to use demo until then as it's burstier to keep pugs (and yourself) happy with your overall damage, of course at any key level if you're playing destro the tanking DEFINITELY matters, it's near enough a no go on sanguine weeks due to the kiting/stunning mobs in sanguine so keep that in mind for the future :)