User blog comment:Xilinoc/Ch. 557 - He Already Set His Life Aside/I Already Threw Away My Life/@comment-9096222-20131113152848/@comment-11051098-20131119201409

@ RingotheDingo:

I don't know how I can explain it better. What I mean is that kenpachi only has Shikai, but still is at the power level of many captains who have Bankai.

As for Yamamoto, he was at a completely different level. He was the most powerful Shinigami who was born in 1000 years, and he also had the most powerful Zanpakutô of all.