Carnage is kinda similar to anihilate spec. It is based on melee attacks and slightly on force. Having your crit on melee high would be a great asset, and along with a high amount of accuracy, since you dont want any misses along the way.
Altho stacking power along it would add up alot, since most of the carnage skills are low but fast dps, so having power and having your min dmg raised up would help. Conssisting above all, would be like having 34% crit unbuffed with 75% surge and above 103% accuracy to make it at its most efficiency.
Carnage is implying alot of rapid dmg but having only slight chance to get your force scream crit, main reason y i find carnage a waste of spec, since you can easily get your force scream if you have your crit rate high enough.
Having for example 30% crit on your melee attacks, will grant you above 37% crit on your force, so looking at it, you`ll have a high chance of almost criting all the time with force scream.