Well, if you have read the interview of Kubo during one month break then its pretty easy to guess. He said her role and bankai will be revealed.
Its good to see something new even if asspulled, though I am not ready for another training arc whether its Ichigo or Zenpachi.

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Huh. It's been a while since there's been a Bleach chapter I didn't hate/be bored by. I actually like this twist about Unohana. We've always had evidence that she is a lot stronger then she looks and this explains it pretty well. I do have more questions about this (why did she change her name, why did she join the fourth division, why hasn't she actually fought yet if she's so strong, etc.), but I'm sure those will be answered later, hopefully in a way that makes sense.

Well from a logical point of view and kind of predictable outcome is that she got sick of fighting or something that made her incapable of really fighting to her fullest, which is why she learned healing, just think of her as an alternative version of Tsunade from Naruto before being influenced by Naruto, that's the only thing I can come up with but it is severely predictable and would be kinda lame if it would be really the reason.