2008-09: Yaroslav Kosov trained in the Magnitogorsk sports school as well as competing with the Metallurg '93 team.
2009-10: Kosov played for Metallurg Magnitogorsk-93. He was selected by Metallurg in the 3rd round (70th overall) of the KHL draft.
2010-11: Kosov scored 11 goals with 10 assists in 43 games for Stalnie Lisi (Metallurg Magnitogorsk' junior team) during the MHL regular season. In 17 playoff games, he scored six goals with 1 assist as Stalnie Lisi (Steel Foxes) advanced to the Kharlamov Cup finals and finished second to Red Army. Kosov was not listed on Central Scouting's final European skaters rankings but was selected by the Florida Panthers in the 5th round (124th overall) in the 2011 NHL Draft.
2011-12: Kosov appeared in 27 KHL games with Metallurg Magnitogorsk and also played with the club's MHL junior team the Steel Foxes. He also skated in the 2012 U20 World Junior Championship for Russia. Kosov scored 4 goals with 5 assists and was plus-six with 6 penalty minutes; averaging just over 8 minutes of ice time per game with Metallurg. Magnitogrsk finished second in the Kharlamov Division and reached the East Conference finals. Kosov was minus-two in seven playoff games; averaging less than three minutes of ice time. In 12 games for Steel Foxes he scored 6 goals with 4 assists and was plus-five with 6 penalty minutes. Kosov scored 2 goals with 2 assists and was plus-five in seven games at the WJC. Russia defeated Finland in the bronze medal game.
Kosov, like NHLers Evgeny Malkin and Nikolai Kulemin, played his youth hockey in the Eastern Russian mining city of Magnitogorsk. Kosov has the ideal size for a power forward and possesses above average stick-handling and passing skills. He is strong and quick on his skates and drives the net with authority. Although he does not have a sniper’s mentality, he controls the puck well in traffic, and has the kind of hand-eye coordination that allows him to get the puck out of a pile of skates and put it in the back of the net.
Kosov is set to play a full season with Mettalurg Magnitogorsk in the KHL, where he will inevitably see more ice time than his 8:07 minutes per game of his rookie year. Still only nineteen years old, if Kosov can continue his production rate at the KHL level (despite his limited ice time, over 27 games last season Kosov led Mettalurg in points-per-60-minutes of ice time), his star will rise quickly in Russia, and in North America. Kosov will undoubtedly see more international ice time, as well, while playing for Russia in the World Junior Championships this winter.