Board Thread:General Discussion/@comment-3422208-20140914021318/@comment-1268838-20140918232040

Kenpachi is listed as having Immense Spiritual Power, which puts him well above their level - as far as know from what he said, he fought each of them one by one. It is the same case for Yamamoto and his "fight" with Driscoll. And stretching even further, Shaz was evidently one-shotted by Ichigo, who is also under the Immense category. There is no contradiction in them being as powerful as captains while still getting destroyed by one particularly powerful one.