The O's made Jefferson a fourth-round pick in the 1968 amateur draft and the right-hander reached the majors in 1973. He spend three of his nine big league seasons in Baltimore, going 7-7 with a 4.13 ERA in 42 games, 17 as a starter. When he started, he usually finished, recording 12 complete games in orange and black from 1973-75.
Jefferson was traded to the Chicago White Sox in June 1975 for first baseman Tony Muser and was taken by the Blue Jays in the expansion draft in November 1977. He was a mainstay in Toronto's inaugural rotation, going 9-17 with a 4.31 ERA in 33 starts. He also pitched for Pittsburgh and California in his career, finishing 39-81 with a 4.81 ERA in 237 lifetime games.
After being granted free agency by the Angels in November 1981, the Orioles re-signed Jefferson. But the reconciliation didn't last long - Jefferson was released on April 1, 1982. He resurfaced in 1983 with the Angels' Triple-A Edmonton affiliate, but his comeback ended after three games and he retired.