User blog comment:Xilinoc/Ch. 569 (You've been hit by / You've been struck by / Senbonzakura~)/@comment-24113610-20140223232155/@comment-4957813-20140224140348

Canonically, Kira has only been shown to hold his own against Rangiku and beat one Fraccion, Hisagi beat a Fraccion and only beat the much stronger Tosen because Tosen was distracted, Momo and Rangiku have both struggled to fight Fraccion, Iba we have no idea how strong he is since he was never shown in a combat situation, while Rukia was capable of defeating an Espada. She only struggled against Aaroniero because of the anxiety of destroying Kaien. You are seriously downplaying the strength of Rukia.

Let's not forget back before they went to Hueco Mundo, in the fight against Di Roy, Rukia's strength, despite being an unseated officer, was described to be at the level of a seated one. The only reason why she wasn't was because of Byakuya.