Youth

As a youth, McCoshen played in the 2007 Quebec International Pee-Wee Hockey Tournament with a minor ice hockey team from Minnesota.^[1]

High school

McCoshen played three seasons (2010–13) of Tier 1 junior ice hockey with the Waterloo Black Hawks of the United States Hockey League (USHL).^[2][3] He was selected to both the 2012 and 2013 USHL/NHL Top Prospects Game,^[4] and in his final season, he was further recognized for his outstanding play when he was named to the 2012–13 USHL First All-Star Team.^[5]

College

McCoshen got off to a strong start in his NCAA campaign at Boston College with a 13-point year as a top defensemen for the Eagles ice hockey team.^[6][7] He scored Boston College's first goal of the season and was on SportsCenter's Top-10 plays for his goal-saving effort in a game against the University of Minnesota. He also earned rookie of the week honors for his game-winning goal against the University of Massachusetts Lowell during the NCAA tournament.^[8] McCoshen played at the 2014 World Juniors for the United States.

Florida Panthers

At the completion of his junior year with the Eagles in 2015–16, McCoshen concluded his collegiate career in signing a three-year, entry-level contract with the Florida Panthers on June 19, 2016.^[9]

McCoshen finished his first professional season skating in three NHL games, his NHL debut coming on April 6, 2017, in a 6–3 loss to the St. Louis Blues. He also recorded his first point (an assist) in the game.^[10]

Chicago Blackhawks

On October 22, 2019, McCoshen was traded by the Panthers to the Chicago Blackhawks in exchange for Aleksi Saarela.^[11] He was assigned to report to the Blackhawks AHL affiliate, the Rockford IceHogs. Unable to earn a recalled to the Blackhawks, McCoshen remained with the IceHogs, posting 2 goals and 8 points in 56 games before the season was cancelled due to the COVID-19 pandemic.

As an impending restricted free agent, McCoshen was non-tendered a qualifying offer by the Blackhawks, and was released to free agency on October 8, 2020.^[12]

Minnesota Wild

On October 19, 2020, McCoshen agree to a one-year, two-way contract with the Minnesota Wild.^[13] McCoshen was assigned to the AHL and played exclusively with affiliate, the Iowa Wild for the 2020–21 season, collecting 4 assists through 11 contests.

Later years

As a free agent from the Wild, McCoshen was un-signed over the summer before accepting an invitation to attend the Vegas Golden Knights 2021 training camp in preparation for the 2021–22 season. After participating in training camp and pre-season, McCoshen was re-assigned to join AHL affiliate, the Henderson Silver Knights on a professional tryout basis on October 2, 2021.^[14]

As a free agent from the Silver Knights in the following off-season, McCoshen signed his first contact abroad in agreeing to a one-year contract in Finland with Ässät of the Liiga on August 15, 2022.^[15] McCoshen played 59 regular season games in an Ässät jersey only missing one game. He scored 7 goals and 21 assists and a total of 28 points. McCoshen appeared in 8 playoff games and put up 4 points which were all assists.^[16]