West compiled a 7–9 win–loss record along with a 5.10 ERA and 92 strikeouts over a career-high 146+1⁄3 innings in 1990, which ended with a hamstring injury.[1] During spring training the following season, he injured his elbow before straining his abdominal muscles immediately ahead of his intended comeback. This consequently delayed his first start of the 1991 season to July 4.[5] He was utilized mostly as a relief pitcher towards the end of the regular season.[5][7] In the 1991 American League Championship Series, he appeared in two games against the Toronto Blue Jays, pitching 5+2⁄3 innings while allowing just one hit and no runs and being the winning pitcher in Game 5.[1][5] He then appeared in two games during the World Series that year but recorded no outs, allowing two hits, four runs, four walks in six total batters, resulting in an infinite ERA.[1] The Twins ultimately won the championship in seven games.[8]
During the 1992 season, West was limited to 9 games (3 starts) and had a 1–3 record with a 6.99 ERA in 28+1⁄3 innings pitched. He was traded at the end of the year to the Philadelphia Phillies in exchange for Mike Hartley.[1] He was used exclusively in relief in 1993,[9] recording a career-best 2.92 ERA that year and finishing second in the National League (NL) in games pitched (76). The 76 games he pitched in set a Phillies record for a lefty.[10] He went on to pitch three games in the 1993 World Series, which the Phillies lost to the Toronto Blue Jays. In the 1994 season, West finished fourth in the NL in walks (61) and wild pitches (9), and seventh in losses (10).[1] He missed the majority of the 1996 season due to injury,[3] before moving to Japan the following year to pitch for the Fukuoka Daiei Hawks.[4] He returned to MLB in 1998, pitching six games for the Boston Red Sox and playing his final major league game on September 4 that year, at the age of 34.[1]