He was Black Gold"s leading scorer as a junior with 61 points after leading the team in goals as a sophomore with 26. Markell finished his career with 235 points, including 102 career goals. He also had 133 career assists.
Markell was voted Black Gold"s outstanding forward in 1978 and 1979.
After going undrafted, Markell played 55 National Hockey League games: 52 with the Winnipeg Jets, two with the Saint Louis Blues and one with the Minnesota North Stars. In his National Hockey League career, Markell scored 11 goals and 10 assists.
Markell served as the head coach of the Ohio State University ice hockey team from 1995 until the end of the 2009-2010 season. The seventh Buckeye head coach, he led the team to the National Collegiate Athletic Association tournament six times, marking the only appearances in program history, with an National Collegiate Athletic Association Frozen Four appearance in 1998.