User blog comment:MarineroLelouch/Power Ranking and Classes./@comment-3290324-20140211014255/@comment-24467372-20140211223331

@Chaos: I know that but that was some time ago. Erza gets new asspuls and power-ups every arc. Sometimes multiple power-ups.

Erza and Mira were stated to be equal in the past......Erza has Nakagami Armor and Second Origin now...not to mention she fought incredible foes that Mirajane hadn't faced. That makes her grow stronger.

Mashima also makes it look like Gray is equal to Natsu but Natsu can probably one-shot him with the high-end power-ups he's receiving.

This is because of fan-service I believe. Gray's or Mira's fans don't want to see their favorites be paling in comparison to Plotsu and Erza.