Yeah, it is nonrealistic to expect they are going to play every game at the level they grinded the EG wins at this point. They will definitely still bomb out, and likely also succeed. The question will be that can they constantly improve and within 6 months get away from those bombing out games.
Mouz is great example on this. It took them over 9 months to get good, but once they got there, they have been so stronk. And same for AleksiB ENCE as well. It took them that 9 months to win first DH Open, and rest is history. And Vitality also.
I'd say only exception to this so far has been G2. They have improved ridiculously fast. But on the other hand, the rumor was that G2 started praccing right after major, so they have 6 months already.