McGlothen was the Louisiana high school tennis champion for three years and then attended Grambling State College. He came up with the Red Sox but had his first full major league season (1974) with the Cardinals, pitching in the All-Star Game and finishing at 16-12 (2.70). He won 15 games in 1975, and, on August 19 against Cincinnati, struck out the side on nine pitches. He spent much of 1977 on the Giants’ disabled list with a bad shoulder, but won 13 for the Cubs in 1979 and 12 in 1980. McGlothen was killed in a fire at age 34.