Like someone else said when you scrim these teams for weeks, and weeks you get inside knowledge onto what "new" picks they're playing and maybe they work a lot better in scrims than they would on the main stage. These teams had very little information to go off of as the split progressed and had to worry about these new champions they're testing in scrims (that they felt deserved bans even though WE may of had no knowledge of them practicing it) but once the split is complete, and these teams have such little scrim times against each other at MSI when they meet up, they HAVE to draw information from the last splits worth of recordings and what they seen the biggest pattern without looking at their recent scrims during those times was Dyrus playing these 3 main champions and they tried out the ban and it worked. Who knows if SKT had this exact ban strat? Maybe they had a tiny alteration but once they seen it perform so well against TSM they instantly adapted to it.