The Chicago Cubs selected Plummer from the Cardinals on November 28, 1967, in the Rule 5 draft.[1] Plummer made his MLB debut on April 19, 1968.[3] He spent nearly all of 1968 on the bench and catching in the bullpen in Chicago due to the rules on sending Rule 5 drafted players to the minor leagues. Plummer made his major league debut with the Cubs on April 19, 1968, at the age of 21 in a 9–2 road loss to the Cardinals. Pinch-hitting for Chuck Hartenstein, he struck out against Hal Gilson.[4] He had only one more at-bat that season and played in just two games.[5]
Plummer's career as a backup catcher was profiled in a Sports Illustrated article in July 1977. "I've always wondered how Bill would do if he played two months straight," said Pete Rose. "He's a physical fitness nut, and if hard work means anything, he would do all right." The article's writer said of Plummer, "He is a private person. He hoards his time and spends it with his wife Robin and two daughters, Gina and Tricia. He doesn't drink, works out, jogs and plays tennis, and during the winter he labors on his father-in-law's northern California cattle ranch."[9]
Plummer was the Mariners' bullpen coach in 1982, 1983, 1989, and 1990, and third base coach for the second half of 1988 and 1991. When third-year managerJim Lefebvre was fired after the 1991 season, the franchise's first with a winning record,[16] Plummer was promoted for 1992.[17][18] Seattle finished in last place in his only season as manager, with a 64–98 (.395) record,[19][20][21] and Plummer was let go in October.[22][23] The club had been sold in July,[24][25][26][27] and he was succeeded in November by Lou Piniella for the 1993 season.[28][29][30]
Plummer spent 1993 and 1994 in the Colorado Rockies organization, starting the 1993 season as the AZL Rockies pitching coach and ending the season as the major league bullpen coach in Denver. In 1995, Plummer returned to managing with the Jacksonville Suns, the Detroit Tigers' Double-A affiliate. In the spring of 1996, the International Division of Major League Baseball sent Plummer and other coaches, including Fernando Arroyo, Jim Lefebvre, and Greg Riddoch, to serve as official advisors to the upstart Taiwan Major League.[31]
In 1996, Plummer converted Tigers third baseman Phil Nevin into a catcher in Jacksonville.[32] The Tigers fired Plummer from Jacksonville at the All-Star break, despite winning the Southern League first-half championship, and Plummer finished the season managing the Billings Mustangs in Cincinnati's farm system.[33]
In 2013, Plummer served as manager of the Diamondbacks' Single-A affiliate Visalia Rawhide of the California League in his 22nd season as a minor league manager.[37] Through the 2013 season, he had a career minor league managing record of 1351–1253 (.519).[37] In 2014, Plummer reassumed the role of Arizona Diamondbacks catching coordinator. Plummer announced his retirement at the end of the 2017 season, with a career managerial record of 1583–1459 (.520). Plummer is a member of the Shasta County Sports Hall of Fame, Sacramento Area Baseball Hall of Fame, and Northern California Sports Association Hall of Fame.[38][39][40]
From 2018 to 2023, Plummer was the hitting coach, catching coach and bench coach for the summer collegiate Redding Colt 45s.[41][42]
Plummer's father, William Lawrence Plummer, pitched in the Pacific Coast League from 1921 to 1927, and his uncle, Red Baldwin, was a catcher in the Pacific Coast League from 1915 to 1931. The elder Plummer and Baldwin were teammates in 1924 and 1925 with the Seattle Indians. Plummer's grandson, Conner Menez, has played in MLB.[44]
Plummer's former player Edgar Martinez was inducted into the National Baseball Hall of Fame in 2019, and specifically mentioned Plummer in his acceptance speech as having been an important coach during his minor league career.[46]
In October 2021, a documentary entitled Plum: A Baseball Life, about Plummer's 53-year baseball career, was released.[47][48][49]
Plummer died on March 12, 2024, at his home in Redding, California, after a heart attack.[50][51] He was 76.