Originally Posted by
Jmickey
Honestly, the best thing you or this lock could do is import his armory into SimulationCraft and see what pops up. Haste and Crit seem to yoyo a fair bit for Destro at lower gear levels and even going into the higher gear levels, but neither is way ahead of the other, and which is better is totally dependent on individual setup.
Warlock Simcraft Thread: elitistjerks.com/f80/t110222-simulationcraft_warlocks_cataclysm_edition/
Download from here: code.google.com/p/simulationcraft/downloads/list
You can also point him towards the Destro link in my Sig. Hopefully the information there can be helpful.
Only at certain thresholds. Fully raid buffed the damage Immolate or Corruption does at 1200 haste and 1400 haste is no different. Having said that, if the warlock in question is missing the 5% haste buff in a raid, then he does not have anywhere near enough haste.