User blog comment:Eduardovongola/Renji Overpower/@comment-20612734-20131228150049/@comment-5398287-20131230230545

I'm still not understanding your reasoning. The whole point of the Royal Training is to immensely strengthen those who undergo it. It makes perfect sense that Renji is captain-level now, and as explained elsewhere, it's not necessarily that he's more powerful than Kensei and Rose, just that he's not making the mistakes they did and is thus winning.