It was a game in 1980 that first put McMahon in the national spotlight. Then a junior at BYU, he rung up gaudy statistics that were derided by critics as coming against weak opposition. Then, in the Holiday Bowl that December, he led the Cougars back from a 45-25 deficit in the final 4:07 to stun Southern Methodist University 46-45. The performance put him on the map for the following 1981 season, in which he again put up stellar numbers and was drafted by the Bears in the first round of the 1982 NFL Draft.
McMahon won the Bears' starting quarterback job as a rookie and was named to several All-Rookie teams when he nearly led the team to the playoffs. But it wasn't until 1984 that the Bears broke through, reaching the conference finals before losing to the San Francisco 49ers.
In 1985, the Bears won their first 12 games and finished 18-1 for the season. McMahon became a media darling not only for his outstanding play on the field, but also his personality, perhaps best summed up in a rap record made by the team, in which he proclaims "I'm the punky QB known as McMahon." He ended the season with a strong performance in Super Bowl XX, won 46-10 by the Bears over the New England Patriots, and earned a spot in the Pro Bowl.
He battled injuries for the rest of his career, although at one point between the 1985 and 1987 seasons, he won 23 consecutive regular-season starts. But the Bears never made it back to the Super Bowl, and McMahon was traded to the San Diego Chargers prior to the 1989 season after a fallout with coach Mike Ditka.
He managed two more full seasons as a starter, in 1991 and 1993 while still battling injuries, then spent three more years as a backup. He retired following the 1996 season, in which he won a second Super Bowl ring with the Green Bay Packers.
Although best-known for his off-field antics in the Bears' heyday, McMahon also had a reputation as a heady quarterback with an uncanny ability to read defenses, and it was this talent that kept him in the game for years after injury had wrecked his physical skills.
He is also known for his trademark sunglasses. McMahon wears them for medical reasons; in a childhood accident, a fork was stuck in one eye. While his vision was saved, the accident left that eye overly sensitive to light.