EDG played really well, can they actually keep this up against better teams?
Nah. EDG seems way too cocky and just pushed like mad men. I watched both of the games closely. They showed 0 respect, and mostly won aim duels, and also ONS didn't win any aim duels, other than eko and bazzi maybe. Poor performance from ONS, they couldn't read simple pushed from EDG and didn't trade well. Against a more disciplined japanese team or maybe damwon, EDG wont have the same performance for sure. They are good, but Northeption, CR and Damwon are clearly a tier above them.
It's understandable though, from how they play any sane person would question edg's approach. I just know from my inside man that they scrimmed an Indo top team and they said EDG has a knack for small details, though that's not saying they can use their strat well against similarly prepared team on a real tourney, not just scrims.