User blog comment:IamJakuhoRaikoben/Chapter 477: Transport, Review./@comment-26271908-20160314174631/@comment-7418318-20160314204556

If she can angle her body in a way that she uses Ajeel as a shield, it'd be fine I think. The problem with that is that it only partially works in the manga, since the blast came not directly behind Ajeel, but slightly to the side, which should have resulted in Erza being hit at the very least on her side. Changing the angle by 45 or so degree would make all the difference.

Still very convenient that they just happened to stand perfectly aligned, but better convenient than mysteriously being unharmed by something that should harm her.