Board Thread:Theories and Speculation/@comment-3001903-20151205022433/@comment-3965545-20151210011531

Nagato never lost control.. he summoned the Mazo himself and then purposely linked himself to it.. he then slaughtered every enemy there except Hanzo. Nagato only lost control before he finished his training with Jiraiya.. anime just likes to add extra shit that never happened in the manga.