Honestly, I think we won because Lee Sin played terribly during the Yongssam teamfight

This was a teamfight where Jarvan IV had been removed, and Oner felt like he was diving blindly without any thought.
Because Lee Sin died without doing anything, even a well-fed Syndra died immediately after her ultimate was wasted.
Rumble should have wiped everyone out, but because Yuna-ra (Yuna) grew so quickly, it created a situation where Yuna could outplay Rumble.
After that, it didn't look like KC had any chance of winning due to the team composition gap.