User blog comment:Xilinoc/Ch. 554 - Desperate Lights/@comment-4639012-20131023153257/@comment-4639012-20131023154104

It may well be that, while Yhwach has accounted for the Shinigami regaining their Bankai, he hasn't accounted for the manner in which Urahara has devised it. By which I mean that he may not realise that upon regaining their Bankai, the Shinigami (briefly?) adopt a hollowfied version of it. That could be the power which either levels the playing field or tips the balance in favour of the Gotei. All I've said is conjecture, naturally. But hopefully some of you see where I'm coming from.