2006-07: Mat Clark was the 11th selection for the Brampton Battalion in the 2006 OHL Priority Selection. Played for the Brampton Capitals Jr. A, where he scored two goals and seven assists while adding 50 penalty minutes in 47 regular season games. Clark added a goal and an assist in 8 playoff games for the Capitals.
2007-08: Clark once again suited up for the Brampton Capitals Jr. A club, where netted six goals and added 11 assists while picking up 82 penalty minutes in 46 regular season games. Clark picked up a goal and four assists in 8 playoff games for the Capitals.
2008-09: This was Clark's rookie season in the OHL, appearing in 63 regular season games for the Brampton Battalion. Clark scored three goals and added 20 assists while racking up 91 penalty minutes. He added five assists in 21 playoff games for the Battalion, while adding 37 penalty minutes.
2009-10: In his second season in the OHL, Clark posted 7 goals (all on the powerplay) and 16 assists in 66 games. He also managed a plus-1 rating and 88 PIM. He was then signed to an entry-level deal by Anaheim and assigned to the Manitoba Moose of the AHL, where he made one appearance.
2010-11: Clark skated in all 80 games for AHL Syracuse and endured the baptism by fire that can be expected when making the jump from junior to pro hockey as a 20-year-old. After a difficult first half he appeared to show signs of development in the latter part of the season. Clark led the Crunch with 128 penalty minutes and scored 2 goals with 14 assists. His -18 plus/minus was tied for worst on the team but could at least partially be attributed to him logging major minutes and the Crunch's overall team struggles.
2011-12: Clark made his NHL debut – finishing minus-two while averaging 11 minutes of ice time in a pair of April games with the Ducks. In his second pro season, Clark skated in 62 games for the Ducks AHL affiliate Syracuse, suffering an injury in February that kept him out of 13 games. He was a much-improved minus-one with 1 goal and 11 assists and had 72 penalty minutes. The Crunch reached the AHL playoffs after finishing fourth in the East Division. Clark scored 1 goal with 1 assist and was plus-2 with 11 penalty minutes in the four game series against Saint John's.
2012-13: Clark spent his third pro season with Ducks' AHL affiliate Norfolk. He appeared in a team-high 71 games, scoring 1 goal with 9 assists and was -13 with 79 penalty minutes. Norfolk finished fifth in the East Division; two points out of an AHL playoff spot. Clark was re-signed as a restricted free agent by Anaheim to a one-year contract in July, 2013.
Clark was touted as a diamond in the rough with the potential to be physical in his own end and effective offensively. His rookie season in the AHL was a disaster, however. While he has grown more reliable this season, his numbers have not really improved and it remains difficult to identify any areas where he really jumps off the ice at an observer.
Clark has really yet to prove his ability as a rough and tumble defenseman at the AHL. As a whole, defensive-defensemen take a bit longer to develop but Clark has the better part of two seasons under him and has yet to improve in his defensive zone play or his foot speed. His offensive numbers have stagnated and he needs to start locking down his defensive game if he wants to reach an NHL bottom pairing in the future.