User blog comment:IamJakuhoRaikoben/Chapter 484: The Monstrous Six, Review./@comment-5708675-20160510182750/@comment-5303512-20160511142516

Well, Mirajane did manage to defeat Sayla (with support of course)

Funny thing about Mirajane as an S-Class wizard compared to Erza, Hiro said on Twitter once that Mirajane is stronger than Erza but Erza has more determination.