User blog comment:Lord Zeref Dragneel/Top 25 most powerful characters/@comment-25111584-20150812160455/@comment-3290324-20150813175910

Mashima is terrible with consistency with power levels and feats. That much is clear to anyone reading/watching Fairy Tail who isn't mentally challenged. So it doesn't surprise me at all that the stats for some of these characters would be inaccurate. Mashima himself has even said that he doesn't plan ahead much at all when writing his manga. However, Natsu, Gray, Gajeel, Erza, and Mira aren't random side characters whom Mashima could easily change his mind about. These are main characters he's had in his series for years. If those three were stronger, why would he put their stats lower? Correct answer? He wouldn't. It doesn't make any sense whatsoever. Again, no one is saying that stats are definitive proof of how all these characters rank in strength, but to ignore them in their entirety would be ridiculous.

And no one is saying that the power tiers couldn't have changed. I just don't find it likely. :/