I think it's time to lay this power level thing to rest. Yes, there are inconsistencies and yes if you try you can actually explain (some of) them. So Ichigo easily KO'd a guy who, 300 chapters later, turns out to have been awesome. Big deal. Personally it doesn't bother me THAT much.
What makes this bad is not the weird power level. It's the fact that, the reader had no connection to this guy whatsoever. The in-universe characters might've known about his abilities and how important he was and are therefore shocked.
We readers, however, did not know about all this. Hence the comments on last weeks chapter ("who cares, if they guy we saw like two times in 480 chapters died"). So, to me, this chapter seems just like a really cheap attempt to make the guy look important and try to get some emotion out of the readers. But it just doesn't work that way. 90% of us STILL don't care about his death. Because giving us some infodump about how great he was really doesn't make up for him being barely in the manga and doing almost nothing for about a decade.
So, this whole thing went something like this:
Everyone: "Kubo, why do no important characters ever die in Bleach?"
Kubo: "Oh yeah? How about this: I kill Sasakibe off. That'll show 'em!"
Everyone: "um...we were talking about IMPORTANT characters that actually had some impact on the series so far"
Kubo: "You know nothing! This guy was uber important and you should be sad! Want some proof? Here, have some other characters narrate about his awesomeness. Ha!"
Everyone: /facepalm
It's just bad writing. "Show, don't tell". If we had seen him being important/awesome and/or doing SOMETHING except standing behind Yamamoto at all times, this would've been a different story and all of this would've gained some credibility. But Kubo simply telling us "he was awesome" just doesn't cut it. It just fails to make his death have any impact whatsoever on the reader.