[5][6] After college graduation, Brock signed a one-year contract with the Winnipeg Blue Bombers and was a starting quarterback in 1975.

That season, the team traded away their aging star passer Don Jonas to the Hamilton Tiger-Cats for the much younger Chuck Ealey.

When Brock left the Blue Bombers, he held team records in the following career passing categories: yards (29,623), completions (2,168), attempts (3,777), touchdowns (187), and interceptions (129).

[13] Hamilton lost the East Division Final to the eventual Grey Cup Champion, Toronto Argonauts.

In the 1986 preseason, Brock suffered an injury to his left knee on a tackle by Bo Eason of the Houston Oilers in the first exhibition game on August 2.

Brock underwent arthroscopic knee surgery the following week and went on the injured reserve list the next month.

[15] Although the Rams had Steve Bartkowski as backup, they elected to deal with the Oilers and their new draft pick Jim Everett (who they had a dispute with over signing).

[16] One of five quarterbacks on the roster, he was released by the team after the year ended; he chose to move on from playing football to a coaching career.