You do realize you can win rounds, and fights, while looking bad if your opponent looks worse right? That's literally how fights are scored lol. You don't have to look good, just better than your opponent. DC accomplished that, but that doesn't mean he actually looked unbeatable in his fights while doing so.
You can't tell me with a straight face that this guy:
Was looking unbeatable. And it's right after these that he decides to move down. Which was smart because had he been fighting anybody else who weren't just perplexed at wtf he's doing in the aboves they'd have charged him and hurt him bad. DC had gotten pretty uncoordinated at HW, which came back again when he moved back up again, which LHW helped fix.
And as an aside, I mean, Jones eventually KO'd him precisely because of the mistakes DC was repeatedly making. One of which was from that same Mir fight where Mir hurt him with a bodykick because DC kept overreacting to kicks.
I'm not saying DC wasn't good, I'm just saying he was never unbeatable.