Knepper stepped into San Francisco’s starting rotation, replacing injured John Montefusco, in 1977. The following year, Knepper led NL lefthanders in ERA, led the entire league in shutouts, and won a career-high 17 games. Two straight off-years resulted in a trade to Houston for Enos Cabell, where Knepper became the winningest lefthander in Astros history. He was the NL Comeback Player of the Year in 1981 (9-5, 2.18), finishing second to Nolan Ryan in the ERA race. From 1984 to 1986 Knepper was one of the NL’s best lefties. His 17 wins in 1986 tied the Houston record for lefthanders. He also tied teammate Mike Scott for the league lead with five shutouts. Knepper took leads to the ninth inning in Games Three and Six of the 1986 LCS, but New York rallied to win both, and the series. Knepper dipped to a league-high 17 losses in 1987, but in 1988 a great start propelled him to a 14-5, 3.14 record. He returned to the Giants in 1989 after a terrible start and finished 7-12, 5.13.