User blog comment:Xilinoc/Ch. 571 (Yachiru's gonna wreck it)/@comment-8669536-20140305144023/@comment-10554972-20140305214333

"I actually don't think one can draw any conclusions regarding Yachiru's strength from the division she's in." This is true, but we don't need to base our conclusions about her strength off of her Division, we've already seen plenty to know that she's strong.

1. She's never been shown to be affected by Kenchan's Reiatsu, when Ichigo could barely stand it the first time. This itself is a quite incredible show of strength. In fact, this would probably actually work as a sort of training for her, since she's always so close to it. It'd likely be similar to her being in high gravity.

2. When she first met Ichigo, she was able to jump onto his shoulder from far away without Ichigo even noticing. This shows that she is quite fast.

3. During Ichigo and Kenchan's fight, she got angry at the member of the Inner Court Troops that tried to interrupt her watching of the fight, and showed off a strong and frightening Reiatsu of her own.

4. After Ichigo and Kenchan's fight was over, she picked Kenchan up and easily jumped from building to building. So not only is she quick, she's also quite strong (probably due to her strong Reiatsu).

5. Finally, when Kenchan was fighting Tosen and Komamura, and she went with Ichigo's friends to have them reunite with Ichigo, she ran ahead saying that she would take out the strong opponents and they could handle the weak ones, meaning she's clearly confident in her own strength.

Even though we've never seen her fight before, we still know that she's quite strong, we just don't know how strong yet.