G2 are one of the best teams in the world and are very controlled so they consistently perform, SEN are an S or A tier team playing against C9 who are B-tier normally but played horribly, the other 3 teams they played were straight cheeks. 100t losing to G2 is expected since 100t are ass. Also the other group was basically all 50/50 games so no win would've been considered an upset.