User blog comment:Xilinoc/Ch. 551 - The Burnt Offerings/@comment-11446176-20131004064733/@comment-10630156-20131005031629

It would make sense that the Shiba clan overall is about to make a huge move in this fight. Think about these points that have come to light in the last arc about them.

1. Ganju and Kukaku are in contact with Isshin (by means not known as of yet)

2. Ganju is training with the Fullbringers to fight in this fight

3. Shunsui has most likely met with Isshin when he gave Ichigo's friends soul tickets.

I feel as if Isshin and Urahara have set up another line of attack here, I think it is possible the messenger is Yoruichi because she can go undetected and that the Shiba's might have something bug up their sleeves here. All that above seems premeditated and well thought out. Maybe Ganju and the Fullbrings are forming some sort of rear guard for a planned retreat to a more suitable place to fight them (Heuco Mundo with Kisake maybe?).