User blog comment:Xilinoc/Ch. 580 - THE LIGHT/@comment-2120712-20140515175639/@comment-5398287-20140517190702

Well, let's think about why Kenpachi went down in this chapter. You're right that he's come out of some pretty tough scrapes in the past and remained able to stand and fight. However, what happened to him in this fight is VERY outside the norm, even for him.

He was trapped underground, shot, blown up, hit with god knows what else in some of the more confusing panels, thrown into outer space (where he suffered spacial decompression, which is pretty serious), and finally got NUKED at point-blank range. Even though he was still standing after all of that, he was in bad shape, as evidenced by his internal organs rupturing and his hearing being damaged.

Then we get to this chapter. First, he gets hit with a powerful surge of lightning. As pointed out elsewhere in this comments section, just 50 volts of electricity to dry skin around the heart is fatal to humans, and Candice was clearly packing more power than that in her attack. Then Meninas punched Kenpachi into the ground with enough force to crater it, and given that she can effortlessly pick up and throw a huge building, that was likely equivalent to being hit by a freight train at 80 mph. Then Candice hit him with an even MORE powerful blast of lightning; see above for why that hurts.

At this point, Kenpachi is probably injured beyond anything he's ever suffered in the series so far, hence why he can't even move. It's not so much his power level being inconsistent as it is Kubo being realistic with his ability to tank damage. Sure, he could still remove his eyepatch, but at this point, what exactly would that accomplish? In all the times he's taken it off in the series, it's never heightened his ability to ignore injuries, just made him more powerful in combat. And as for taking it off before attacking Candice, which might have made him harder to injure, he probably didn't think it was worth it yet, since he only takes it off for the strongest opponents and he hadn't yet seen what Candice could do to him.

That's my take on it, anyhow.