A resilient, versatile finesse pitcher, LaCoss was waived by the Reds after 1981 and released by the Royals after 1985 before making the Giants staff as a nonroster invitee to spring training in 1986. He led San Francisco’s 1987 NL West champions with 13 wins, and after an injury-plagued 1988, began the 1989 season as the Giants’ bullpen stopper. The success of Craig Lefferts in relief and injuries to many starters moved LaCoss into the rotation; he finished 10-10 with a 3.17 ERA as the Giants won the NL pennant.
LaCoss enjoyed his best season at age twenty-three, going 14-9 with the NL West champion Reds in 1979 and pitching in the All-Star Game. But by 1983 he was a struggling reliever and occasional starter with the Astros, and he posted a 5.09 ERA in 1985. In 1985 he hit his only two ML home runs in consecutive at-bats.