No. My first instinct was to call it a fluke, but I've since changed my mind. Part of what makes Yair good is that he's so unpredictable. He's arguably the most creative striker in the UFC, and he throws strikes from positions and angles that no other fighter throws.
This wasn't a case of a brawler winging a wild punch and hoping it lands. He saw KZ rushing in, dipped his head to the left, and threw a right elbow where he knew KZ's head would be. The strike took timing, precision, and creativity. He set KZ up for the kill shot, and he landed it. Just because we've never seen a technique before doesn't make it a fluke. Was there a bit of luck involved? Sure. But there's luck involved in almost every KO. And this was certainly more skill than luck.
I hope we get to see this rematch at some point.