Yammy being 0 was also a plot twists
Exactly, I was going to put that as a second example but i figured she could put 2 and 2 together. the espadas ranking has always been a wishy washy system, and changed multiple times throughtout the series. The introduction of priveron espada also had an effect on the ranking as well.
Yes. For me ranks are just like DBZ PLs. They are all BS.
I Believe Aizen ranked the Arrancar for abilities not power.
An Example to this is Zommari. His ability is hax, he can put a tattoo on Ulquiorra and control him.
Another is Wonderweiss, he is a Mod Espada. His ability was to seal Rujjinjakka's flames.