Amateur

MacArthur played minor hockey in his hometown of Lloydminster, Alberta.^[1] He went unselected in the Western Hockey League (WHL) Bantam Draft when he was eligible, due in part to his short stature.^[2] While playing bantam hockey in Alberta, MacArthur put up impressive statistics, despite standing only 5'4".^[2] He recorded 99 points in 38 games during the 2000–01 season with the Strathcona Warriors.^[3] After the season, he was named his club's most valuable player.^[1]

With the numbers MacArthur put up in bantam hockey, he was able to secure a tryout with the Medicine Hat Tigers, but was the club's final cut heading into the 2001–02 season.^[2] As a result, MacArthur played in the Alberta Junior Hockey League (AJHL) for the Drayton Valley Thunder. In his only season in the AJHL, MacArthur recorded 62 points in 62 games,^[3] and helped the Thunder capture a League championship.^[1] During the season, he grew seven inches and Medicine Hat was again interested in obtaining his services.^[2] He subsequently joined the club for the 2002–03 season, putting up 75 points in 70 games as a rookie.^[3] During the summer, MacArthur was then drafted by the Buffalo Sabres in the third round, 74th overall, of the 2003 NHL Entry Draft.^[3]

During his sophomore season in the WHL, 2003–04, MacArthur helped lead the Tigers to the Ed Chynoweth Cup as League champions and a berth in the 2004 Memorial Cup.^[4] MacArthur was the fourth-leading scorer in the tournament with one goal and four assists and was named to the Memorial Cup All-Star Team.^[5][6] The Tigers, however, lost in the semifinal of the tournament to the Kelowna Rockets.^[4] MacArthur played in 58 games during the 2004–05 season with the Tigers and recorded 74 points, while serving as one of the club's alternate captains.^[1] After the season, he was named to the WHL's Eastern Conference First All-Star Team.^[5] MacArthur was remarkably consistent during his WHL career, scoring 75, 75 and 74 points in his three WHL seasons.^[3]

Professional

MacArthur began his professional career with the Rochester Americans of the American Hockey League (AHL), the Buffalo Sabres' top minor league affiliate, for the team's run in the 2005 playoffs, appearing in three games and recording an assist for his first professional point.^[7] He remained with Rochester in 2005–06, recording 53 points over 69 games in his first full professional season.

After starting the 2006–07 season in Rochester for a second year,^[7] MacArthur made his NHL debut for Buffalo on December 19, 2006, against the Montreal Canadiens.^[8] He split time between the Americans and Sabres for the rest of the season, finishing with 63 points over 51 games in the AHL and seven points over 19 games in the NHL.^[7][9] He recorded his first NHL point, an assist, on February 20, 2007, against the Philadelphia Flyers and scored his first career goal against the Ottawa Senators on February 22.^[10]

During the 2007–08 season, MacArthur again spent time with the Americans and Sabres. At the NHL level, he scored eight goals and added seven assists in 37 games, while recording 42 points in 43 games with the Americans. After the season, MacArthur became a restricted free agent before re-signing to a one-year deal with the Sabres.^[11] MacArthur spent his first full season at the NHL level in 2008–09, playing in 71 games with the Sabres and recording 31 points. After the season, the Sabres tendered MacArthur a qualifying offer to retain his rights; he subsequently signed a two-year deal with the club in July 2009.^[12] MacArthur played in 60 games for the Sabres, scoring 13 goals and adding 13 assists before being traded to the Atlanta Thrashers in exchange for two draft picks at the NHL trade deadline.^[13] He finished the season with the Thrashers recording nine points in 21 games.

After the 2009–10 season, MacArthur filed for salary arbitration. After the hearing, he was awarded a one-year contract worth $2.4 million, a significant raise over his previous salary of $1.4 million. The Thrashers chose not to accept the arbitration award, however, and MacArthur subsequently became an unrestricted free agent.^[14]

MacArthur signed a one-year deal for $1.1 million with the Toronto Maple Leafs on August 28, 2010, ahead of the 2010–11 season.^[15] When asked later about his decision to sign in Toronto, MacArthur said, "It was nice to come back to a hockey community."^[16] He later added, "It's the most fun I've had since junior."^[17] Maple Leafs captain Dion Phaneuf, one of MacArthur's teammates at the 2005 World Junior Championships, was influential in the decision to sign with Toronto.^[18] MacArthur scored goals in each of his first four games with the club, becoming the first player in team history to do so.^[19] The following month, he tied his personal career-best when he scored two goals against the Pittsburgh Penguins on October 13. On November 16 he tied a club record by recording three assists in a period against the Nashville Predators. At the end of his first season with the Maple Leafs, he signed a two-year contract extension at $3.25 million per annum on July 5, 2011, thereby avoiding salary arbitration with the club.^[20]

On July 5, 2013, after his contract had expired with the Maple Leafs, MacArthur signed a two-year, $6.5 million deal with Toronto's Ontario rivals, the Ottawa Senators.^[21] On August 19, 2014, the Senators announced they had signed MacArthur to a five-year contract extension worth a total of $23.25 million—carrying a $4.65 million annual average value—set to start in the 2015–16 season.

On February 16, 2015, MacArthur collided with goalie Robin Lehner, resulting in both players being diagnosed with concussions.^[22] On October 20, 2015, Senators general manager Brian Murray announced that MacArthur suffered another concussion during a game against the Columbus Blue Jackets on October 14 and that MacArthur would not be playing in the near future.^[23] MacArthur played only the first four games of the 2015-16 season due to his concussion, although he passed a "baseline test" and was announced to be "medically cleared to play" in late March 2016.^[24]

During a training camp game on September 25, 2016, MacArthur suffered another concussion when newly-acquired Patrick Sieloff hit MacArthur into the boards. Bobby Ryan immediately began a fight with Sieloff, which was quickly broken up.^[25] Sieloff was sent to the Senators' AHL affiliate the Binghamton Senators shortly afterwards.^[26] On January 20, 2017, the Senators announced that MacArthur would not play any of the remaining games of the season on the recommendation of various doctors, despite MacArthur's insistence, that he did not have any symptoms of post-concussion syndrome.^[27] On April 4, 2017, MacArthur returned to the Senators' lineup after an 18-month absence^[28][29] and played in all of the Senators' four remaining regular season games. On April 23, 2017, MacArthur scored the series-winning goal (on the powerplay for a 3-2 win 6:30 into overtime of game six) against the Boston Bruins in their first round playoff matchup.^[30]

At the beginning of training camp for the 2017-2018 NHL season, it was announced that MacArthur had failed his physical and therefore could not attend camp.^[31][32] On November 14, 2017, Senators general manager Pierre Dorion stated it was "highly doubtful" MacArthur would ever play another NHL game.^[33] In 2018, it was reported by Spectrum News Rochester that MacArthur had retired, although MacArthur himself has never made an official statement.

Regular season and playoffs

Junior and professional statistics source^[3]

International

Year	Team	Event	Result		GP	G	A	Pts	PIM
2005	Canada	WJC			6	4	0	4	10
Junior totals					6	4	0	4	10

International statistics source^[39]