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.
2012-13: Kosov appeared in 40 KHL games with Metallurg Magnitogorsk as a 19-year-old and played for Russia in the 2013 World Junior Championship in Ufa. Averaging just under nine minutes of ice time with Metallurg, he scored 4 goals with 3 assists and was -6 with 10 penalty minutes. Magnitogorsk finished third in the Kharlamov Division and lost to Salavat Yulaev in a seven-game first round series. Kosov saw limited ice time in five playoff games and was -1 with no points nor penalty minutes. In seven games at the WJC he scored 3 goals with 1 assist and was +3 with 2 penalty minutes. Russia defeated Canada in overtime in the bronze medal game.
2013-14: Kosov skated for Gagarin Cup champion Metallurg Magnitogorsk as a 20-year-old and also played for the club’s minor league and junior teams. Averaging 9:42 minutes of ice time in a lower line role for Metallurg, he scored 2 goals with 2 assists and was -5 with no penalties in 32 regular season games. Metallurg finished second to Kazan Ak-Bars in the Kharlamov Division in the regular season before rolling through the Eastern Conference playoffs and defeating Praha Lev in the Gagarin Cup finals. Kosov scored 2 goals with 1 assist and was +1 with no penalties in 21 playoff games.
2014-15: Kosov had his most effective year as a pro in Russia, skating in his third season for Magnitogorsk under head coach Mike Keenan. Playing bottom-six minutes, he matched a career-high in goals with four and added a career-high five assists in 52 games. More importantly for his development, he earned regular minutes throughout the season and also appeared in five playoff games.
2015-16: Kosov continued to play for Metallurg Magnitogorsk as the club won its second KHL championship in three seasons. In 53 regular season games Kosov scored 4 goals with 1 assist and was -2 with 28 penalty minutes, averaging 8:25 minutes of ice time. Metallurg finished first in the Kharlamov Division after getting off to a slow start and rolled through the playoffs, defeating CSKA Moscow in a seven-game series in the Gagarin Cup finals. Kosov scored 4 goals with 3 assists and was +4 with 6 penalty minutes in 23 playoff games, averaging just under 12 minutes of ice time per game.
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 played for KHL champion Magnitogorsk Metallurg in 2015-16, finishing with seven points in the Gagarin Cup playoffs after scoring four goals with one assist all regular season. Yet to sign an entry-level contract with the Panthers, he will attend Florida's prospect camp in 2016 looking to earn a roster spot. Kosov impressed in Florida's summer camp in 2014 before returning to Russia. He struggled to find ice time with Metallurg and may have to begin his career in North America in the AHL, something he may not be willing to do .