2008-09: Mattias Sjogren had a solid rookie season in the Swedish Elite league, notching 13 points in 43 games as one of the younger players on Rogle.
2009-10: Got into more games for Rogle as a sophomore, posting 11 goals and 11 assists in 54 games, showing improvement as he gained strength and experience.
2010-11: Moved over to Farjestad, where he improved his point total from 22 to 24 and also registered a plus-five in 51 games. In the playoffs, he helped lead Farjestad to the league championship with nine points in 13 games. Also played for silver medalist Team Sweden in the World Championships, where he notched four points in nine games.
2011-12: Signed by the Capitals as a free agent in June, 2011, Sjogren opened his first season in North America with Washington's AHL affiliate Hershey before returning to Sweden to play for Farjestads. He played 19 games for the Bears, scoring 2 goals with 3 assists and was minus-six with 4 penalty minutes. Sjogren left the Bears at the end of November to play for Farjestads. He scored 3 goals with 6 assists and was minus-nine with 22 penalty minutes in 28 games. Farjestads finished sixth in the regular season but reached the playoff semifinals. Sjogren scored 2 goals with 2 assists and was plus-two with 2 penalty minutes in 11 playoff games. He returned to the Capitals for the NHL playoffs but did not appear in any games.
A highly sought after undrafted free agent, Sjogren ultimately signed with the Capitals in early June. He attended development camp in the summer, where he impressed as truly a man among boys. Scouts laud his physicality, but he has also shown decent offensive ability. In the NHL, he projects to be a third- or fourth-liner, who can wreak havoc on the forecheck but also chip in offensively.