After graduating from Whittier College with a degree in sociology, Colborn studied for his master's degree at the University of Edinburgh in Scotland, where he also starred in basketball as well as baseball, being named all-Scotland.

In 1967, the Chicago Cubs signed Colborn as an amateur free agent. He found himself in Leo Durocher's doghouse after struggling as a young relief pitcher for three years. Colborn was traded along with Brock Davis and Earl Stephenson to the Brewers for José Cardenal on December 3, 1971.^[1]

Colborn was the Brewers' first-ever 20-game winner in 1973, posting a 20–12 record with a 3.18 ERA. He also was named to the American League All-Star team, but did not pitch in the game.

Over the next three seasons, however, Colborn posted losing records (10-13 in 1974, 11–13 in 1975 and 9–15 in 1976) before being traded, along with Darrell Porter, to the Kansas City Royals. In 1977, Colborn won 18 games for a Royal team that won the second of three consecutive American League West titles (all three times, however, the Royals lost to the New York Yankees in the American League Championship Series; Colborn did not pitch in the 1977 ALCS). On May 14 of that year, Colborn no-hit the Texas Rangers 6–0, the first no-hitter by a Royal at Royals Stadium and second overall in that park, after the first of Nolan Ryan's seven career no-hitters (1973). He was dealt from the Royals to the Mariners for Steve Braun on May 31, 1978.^[2]

For eight seasons, Colborn was on Jim Tracy's staff as a pitching coach: from 2000 to 2005, when Tracy managed the Los Angeles Dodgers, and in 2006 and 2007, when Tracy managed the Pittsburgh Pirates.

In 2008, Colborn became the Texas Rangers bullpen coach.

In his career, Colborn won 83 games against 88 losses, with a 3.80 ERA and 688 strikeouts in 15971⁄3 innings pitched.

• List of Major League Baseball no-hitters