Clean, not clean, the reality is Dustin actually outlanded him in the fight with much higher accuracy.
For it being such a short fight, Conor took some big punches that would've stumbled lesser chins.
I expect the rematch to go the same way, Conor is gonna take some big punches closing the distance and he'll have to land something big to win. The chance that Conor can KO Dustin clean or get him behind the ear again is less likely than Dustin playing it smart, being prepared, and dragging Conor into the later rounds for a tko stoppage.