User blog comment:FairyRaven/Fairy Tail Chapter 423: Do It All for Love, Review and Commentary/@comment-27169256-20150309181804

I honestly don't see the problem with Natsu one shotting Blue Note. This is the very least I expect from him if he ever plans on defeating Acnologia with the finale not too far away from now.

I think we can all confirm that Natsu and Gildarts did do some training as it's the only explanation I can see to his monstrous strength unless his power now has something to do with E.N.D in which case it makes sense.