An Overkill change would have required more redesign of the talents and abilities than we were willing to make for a small patch like this. We're also unconvinced it would have fixed the problem alone.
Basically, it might have helped stealth burst, but wouldn't have helped with unstealthed burst, which was still too high in our opinion. Two Mutilates and a Cold Blood Eviscerate within one Kidney Shot duration is a ton of damage, and is possible with unglyphed Vigor and no Overkill. Add a partner or an interrupt or whatever and it can mean death for most players in very few GCD.
Overkill and glyphed Vigor are something we will probably look at for 3.1, depending on how the current wow gold changes shake out.
Dirty Deeds / Mutilate bug
Rogue poison damage / Consequences of changes made to Mutilate
Rogue poison damage had at least two bugs in the system when Lich King launched. When we fixed those bugs, rogue damage dropped significantly. There is speculation that the same thing is true of Dirty Deeds -- that because Dirty Deeds was inflating poison damage more than we realized that rogue damage will drop too much with the Mutilate changes and Dirty Deeds bug fix.
We do not have that concern at this time. We are happy with Mutilate's extra damage to poisoned targets to be 20% with or without Dirty Deeds. We plan to increase rogue PvE damage in other ways, such as through the announced (but not finalized) Hunger for Blood, Killing Spree and Lightning Reflexes changes in 3.1.
Whether the Mutilate change and Dirty Deeds hotfix will be the death knell for rogues in PvP, we will continue to pay attention on it.buy cheap wow gold