Doug was drafted by the Chicago White Sox in the 11th round of the 1983 amateur draft and, after playing in the minor leagues for four different teams, made his Major League debut on May 30, 1986 for the New York Yankees.
Doug was traded in the off-season with Logan Easley and Brian Fisher to the Pittsburgh Pirates for Rick Rhoden, Cecilio Guante and Pat Clements.
Doug had his best years with Pittsburgh, from 1987 to 1992, during which time he regularly pitched over 230 innings and consistently finished in the top 10 in the National League ERA race. Doug went 22-6 with a 2.76 ERA in 1990 en route to winning the National League Cy Young Award and leading the Pirates to the postseason (where they lost in the National League Championship Series to the Cincinnati Reds). His 22 wins that year were a league high; it was also seven wins higher than his second best season.
Doug signed as a free agent after the 1992 season with the Houston Astros. Despite a solid 3.79 ERA and playing for a rising team, Doug posted an abysmal 9-18 record. He improved in the strike shortened 1994 season to 12-6 with a 2.84 ERA.
- All-Star (1994)
- National League Cy Young Award winner (1990)
- Finished 4th in National League Cy Young Award voting (1994)
- Finished 5th in National League Cy Young Award voting (1992)
- Finished 8th in National League MVP voting (1990)
- New York Yankees (1986)
- Pittsburgh Pirates (1987-1992)
- Houston Astros (1993-1996)
- Chicago White Sox (1997)
- Baltimore Orioles (1998)