Lev had the 9-3 advantage because they were better and had more rounds they were allowed to lose because of that advantage. And again: Without the team setting up aspas there would have been no way he broke the kill record.
And it's better for you to believe that as well because either: Lev played uncoordinated and choked 4 rounds and still won. or: Lev played great and Sentinels barely lost to them in 2 close maps. One is the better option to believe for you.