Help with WAR

[Lethallin]

Fracture is always a DPS increase as long as it ticks for the full duration, buffs or otherwise.

Isn't fracture total potency 300?

100 initial, 20 potency for 30 seconds = 10 ticks, so 100 + (20x10) = 100 + 200 = 300?

How is that better then a 500 Fell Cleave?