User blog comment:Miskos3/Fairy Tail Chapter 505: Trump Card, Review/@comment-7418318-20161007151053/@comment-2214433-20161007151911

I think that's what Makarov was implying though, that Mavis plan may have lead them to victory, but some, if not a lot, would have been sacrificed in the process. And he didn't want that, he prefered himself to be the single sacrifice.