Mitchell had a tryout with the Atlanta Falcons of the NFL in 1981 before signing with Ottawa as a free agent. Mitchell played three games for Ottawa in 1981 and 13 in 1982 before being released by the Rough Riders. Apparently Ottawa gave up on Mitchell a bit too quickly as he signed as a free agent with Toronto and won three East All-Star selections in the next three seasons (1983-1985). Despite that success, however, Mitchell was released by the Argos after the 1985 season and signed as a free agent with Montreal. Mitchell played 15 games for the Als in 1986, but Montreal folded just prior to the start of the 1987 season. Mitchell was selected in the second round of the dispersal draft by Edmonton, but played just two games for the Eskimos.
Tackle stats were kept officially for the first time in 1987.