User blog comment:Zathronas/Analysis by an author: Volume 2 episode 3/@comment-2006510-20140808072655/@comment-10380701-20140809035832

It think the issue with Ruby's failure of usage of her Semblance may not just stem from Penny herself.

I mean, just literally some days ago, she managed to performed an awesome maneouver to stop herself during the food fight.

Her full usage of her semblance at that time may have affected how she's not as badass as she was when using it for this episode. This holds no basis though.