2006-07: Marcel Mueller skated in 36 DEL games for Eisbaren Berlin as an 18-year-old in his second season in the league. Eisbaren, coached by former NHL coach Pierre Page, finished ninth in the 14-team German league. Mueller scored 1 goal with 7 assists and had an even plus/minus with 53 PMs.
2007-08: Mueller skated for third-place Kolner Haie in his third pro season in the DEL. He scored 6 goals with 7 assists and was -2 with 61 PMs in 44 regular season games. Mueller skated in all 14 playoff games as Kolner Haie reached the DEL finals and scored 1 goal with 1 assist and 6 PMs.
2008-09: Mueller scored 11 goals with 14 assists and was an even plus/minus as Kolner Haie finished 15th in the 16-team DEL. Mueller skated in 41 of 52 games and had 60 PMs.
2009-10: Mueller posted 24 goals, 32 assists, and 122 penalty minutes in 53 regular season games with Kolner Haie. After finishing tenth, the club was eliminated in the qualifying round of the playoffs. Mueller had 4 assists and 2 PMs in the three-game series. Mueller signed a two-year, free-agent contract with Toronto in July 2010.
2010-11: Mueller made his NHL debut with the Leafs in January in what was an otherwise frustrating first pro season in North America. Mueller was scoreless with 2 PMs, averaging just over ten minutes of ice time, in three games with the Leafs. Mueller skated in 57 games for the Leafs' AHL affiliate Marlies; missing time late in the year after suffering a concussion and at other times being a healthy scratch. He scored 14 goals with 18 assists and was +3 with 44 PMs as the Marlies missed the AHL playoffs. Mueller skated for Germany at the 2011 IIHF World Championship. In seven games for seventh-place Germany he was an even plus/minus with 1 goal and 4 assists.
2011-12: Mueller got off to a fast start, scoring 4 goals with 14 assists for the AHL Toronto Marlies in his first 18 games before struggling with injury issues and inconsistency as the season wore on. He finished with 14 goals and 33 assists and was plus-18 with 71 penalty minutes in 72 games for the Marlies. Toronto finished first in the North Division and reached the AHL Finals. Mueller skated in nine of the Marlies 17 playoff games and scored 2 goals with 3 assists; finishing plus-four with 4 penalty minutes. He was tendered a qualifying offer by the Leafs in June 2012 but signed with MODO in Sweden's Elitserien for 2012-13.
2012-13: Mueller played for MODO in Sweden's Elitserien and played for Germany in the 2014 Winter Olympics qualifying games. He scored 8 goals with 14 assists in 53 regular season games and was -3 with 34 penalty minutes for MODO, which finished seventh and lost to Farjestads in a quarterfinal series. Mueller scored 2 goals with 2 assists and was -2 with 16 penalty minutes in five playoff games. In three games with the German national team he had 2 assists and 2 penalty minutes. In June of 2013 he signed a contract to play for Kolner Haie in Germany's DEL in 2013-14.
Mueller is a big forward at 6’4 who is hard to handle due to his size and skating ability. While he possesses great size, Mueller is still learning how to use it properly. His game, at the moment, has its fair shares of inconsistencies. He shows flashes of dominance and incompetence from game-to-game. When he’s on his game, he’s capable of driving the net hard and winning battles in the dirty areas of the ice to score goals. An addition of aggression in his game would also make him more of a dangerous forward.
Mueller is playing for Kolner Haie of the DEL in 2013-14.
Projection: Inconsistent power-forward with top-nine upside.