User blog comment:FairyRaven/Fairy Tail Chapter 423: Do It All for Love, Review and Commentary/@comment-194.103.203.254-20150309125626/@comment-9595671-20150309133646

I agree with you on both ends. When the first timeskip came it was a week to the Tenrou Team but 7 years to others so he was overpowered till the Second Origin was awakened. Now that he's had a prolonged period of time that was most like 90% training he's obtained a power boost similar to Luffy's.

Also it does seem like usually heroes need to train through old fashioned labor while the villains level up with some power to get more powerful.