User blog comment:Relikz/Chapter 364: Tartarus Arc, Part 1: Immorality and Sinners, Review./@comment-4449950-20131220015154/@comment-1359322-20131220023050

Think about it this way, Natsu goes to rescue Mira and Erza. Then the Oracion Seis + Crime Sorciere team goes to Tartaros' headquarters to wrack things up. This way the OS + CS team gets the spotlight.