280 Raw Potency per target is absurd.
To put into perspective; if you hit two targets with Decimate thats 280*2 right? Thats a total of 560, which is already better than Fell Cleave.
3 Targets? 280*3 which is... You guessed it! 840! 4? 5? 6? The potential is only limited by its range.

This logic applies to all AoE skills.