Why do we think it is true? First of all, Virtus.Pro managed to step their game up significantly over this short period of time. They were crowned as The Defense #3 champions, having defeated Fnatic.EU in the Grand Final this Saturday. Moreover, yesterday VP finished second at their own Russian Dota 2 League, having lost to Dignitas.
Secondly, all of us could see what Ilya "Illidan / Airman" Pevcaev meant, when he said that Sergey allows them to create more openings around the map. It can be exemplified by his blink-stun initiations on Nyx Assassin in the first game of The Defense #3 Grand Final. Additionally, it is worth highlighting his play on Jakiro in both Grand Finals - Sergey created a lot of space and time for his team with perfect stun positioning in team fights.
Last, but not least. There are no real openings for ARS-ART in other CIS powerhouses. Even though he had played in international rosters before, it seems like it is not worth refering to it - VP have proven to be a fearsome opponent, so there is no reason to leave "The Bears".
Yaroslav 'NS' Kuznetsov
Sergey 'KSi' Kuzin
Oleg 'Crazy' Kolensichenko
Ilya 'Airman / Illidan' Pevcaev
Sergey 'ARS-ART / Smile' Revin