User blog comment:FairyRaven/Fairy Tail Chapter 329: Seven Dragons, Review and Commentary/@comment-49.176.34.76-20130430152649/@comment-7418318-20130430153337

Cobra never seemed to be fighting all that seriously. Neither in the Oracion Seis arc, nor in the KotSS arc. It looked more like he was playing with his "victims" than fighting a serious battle against dangerous enemies.

Furthermore in FT motivation can have a massive impact on fighting capabilities. Before he had thrown everything away and fought purely on resentment and bitterness. Now he's fighting together with the people who pulled him out of that morass to protect something.