User blog comment:Scott swag/How stong is Captain Unohana?/@comment-1906999-20100908190838

The truth is, Kubo is the only one who knows how strong she really is because, like you said, she's never been in a fight before. Shinigami, both captains and ordinary Gotei 13 members, have all shown to fear her, which I've always thought was hilarious based on her kind appearance.

I don't really have anything to base this on, but I think she has to be one of the strongest captain in the Gotei 13, with the exception of Yamamoto. I really hope she joins a fight soon, just to prove that all the people who are scared of her are correct in fearing her.