User blog comment:CoolJazzman/Why do you think Yamamoto wasn't giving a promoted to become a royal guard./@comment-8295743-20130417035134/@comment-7658432-20130418004101

They're OP because they steal Bankais. Let Shinigami steal Lets Stil or Volstendeig (spelling? meh.) and they would be OP too.

About Wonderweiss' fight with Yamamoto, when he was suppose to die, he will explode with the flames Old Man conjured bringing the whole Fake Karakura Town to cinders that's why after his fight with Wonderweiss, he couldn't use his sword and instead sacrificed his left arm for a forbidden kido against Aizen.

I put it wrong, I meant to say "Kenpachi is the only one who defeated Stern Ritters" (ASIDE Yamamoto because it's given that he could kill them with his shikai). The point of Old Man can't kill Aizen is true because he took such countermeasures but power-wise, he could.

About the old captains never releasing their bankai, what do you think would happen if Yamamoto released his Bankai in Fake Karakura Town where the other Captains are?