I guess because on paper, Astralis won 10 trophies, 1 major, 1 grand slam in 2018. Navi wins 8 trophies, 1 major, 1 grand slam in 2021. Ofc, I didn't take online vs LAN into consideration. However, if you look at Navi's performances online vs on LAN, there's night and day difference, which also reflects in the stats of Navi players. They have performed far better on LAN, than online.