Mob damage at all level's is completely screwed. Even when capped with good resists some mobs can destroy you in seconds with their damage. Fire mobs are a perfect example of this.
And all of this is compounded by the health bounce issue that still happens all the time, were you take a lot of damage in a hit then after a second or so the actually damage you should take is calculated and your health bounces up to that level.
If you take 2 hits before the bounce/real damage calculation happens you die.