User blog comment:Xilinoc/Ch. 579 - THE UNDEAD 6/@comment-1268838-20140507172539/@comment-24503264-20140508110338

Aizen is behind everything. He let himself be sealed by Urahara just so he could troll Yhwach. He had Kenpachi and Unohana fight to the death, just so he could more easily overthrow Soul Society once he returns (one captain down without lifting a finger). He had Gremmy fight against Kenpachi just to get rid of the Visionary. He had Kon go to the Soul King dimention just for the lulz.

It's all going according to his schemes.