After three years in the Canadian Football League, he returned to the NFL as a some-time starter for the Detroit Lions in 1991, compiling a 10–5 record over three seasons. Kramer's nickname in Detroit was "Brass", a media-friendly redaction of "brass balls". The moniker apparently originated after Kramer called an audible on his first series as Lions' quarterback, having just replaced the injured Rodney Peete. One Lions' offensive lineman turned to another and said, "This guy's got brass balls." Kramer proved to be quite successful as a signal-caller in 1991 and the nickname stuck. His other nickname was "Cosmo", which was due to him having the same last name as the character Cosmo Kramer from the popular TV show, "Seinfeld". He shared QB duties with Peete and Andre Ware. In the 1991 playoffs, he led the team to a 38–6 drubbing of the Dallas Cowboys, on a franchise postseason record 29 completions for 341 yards and three touchdowns. He also had the team's only touchdown in a loss to the Washington Redskins in the championship game. He remains the franchise leader in postseason completions (50), attempts (71), yards (590), and sacks (5) in a single season. Combined with a loss in the 1993 postseason, he holds the career franchise postseason records for touchdowns (5 with Tobin Rote), passer rating (99.2), sacks (9), and yards per attempt (8.2) as well.