A fireballing Dominican with a good forkball, DeLeon flirted with no-hitters in his second and third ML starts in 1983, carrying one into the seventh against the Padres, and the other into the ninth against the Mets. But he went 2-19 for Pittsburgh in 1985, leading the NL in losses – and received a raise. He was dealt to the White Sox for Bobby Bonilla in 1986, went 11-12 in 1987, and was sent to the Cardinals for Lance Johnson and Rick Horton. He eventually blossomed under manager Whitey Herzog, going 16-12, 3.05 in 1989 and leading the NL in strikeouts. The following year, however, he posted the second 19-loss season of his career. DeLeon later developed into an effective reliever, and was traded from the Phillies back to the White Sox for Bobby Thigpen in August 1993 to aid Chicago’s stretch run.
