User blog comment:Xilinoc/Ch. 574 DEATH IN VISION/@comment-2211792-20140326135532/@comment-24739477-20140326204846

1. Perhaps Kenpachi was never actually there, until Yachiru imagined him into reality. As well his reiatsu might only be a figment of the Shinigamis' imagination - only it's actually become reality once they've heard Gremmy talking to "Kenpachi" & "setting the stage".

2. He's learned to actually control his power (i.e. "I wasn't planning to cut steel").