Central Michigan University's baseball team played at the facilities that would eventually become the original Theunissen Stadium starting in 1949. The University Baseball Stadium (informally known as Alumni Stadium) was built on the corner of Preston and East Campus Drive and was part of a larger collection of outdoor athletic facilities known as Alumni Field. The stadium hosted games from 1949 until 2001. Located in the heart of CMU's campus, baseball games could be heard from classroom windows and were often attended by students on their ways to and from class.
Alumni Stadium was rededicated in 1987 as the William V. Theunissen Stadium. It was named after Bill Theunissen, a former baseball coach with the University who led the team to a 151-114-1 record during his tenure in the 1950s and early 1960s. At the time of his retirement in 1986, Theunissen was the winningest coach in CMU baseball history, and he currently ranks fourth on that list. Besides playing a variety of sports and coaching baseball at CMU, Theunissen became a professor of health and physical education before serving as dean of the School of Health, Physical Education, and Recreation (later renamed the School of Education, Health, and Human Services).
The stadium was improved a number of times during its tenure as home of CMU baseball. The University built a new scoreboard in 1970, replacing it with a more modern one again in 1990. The stadium underwent a significant renovation in 1980-81, when the University spent $350,000 for improvements including the installation of bleacher-style seating, a ticket booth, concession stands, and restroom and media facilities.
In 2002, the new Theunissen Stadium opened on West Campus Drive as part of an effort to concentrate all of the University's athletic facilities on the south end of campus. At the closing ceremony for the old stadium, Bill Theunissen joined over a hundred former players to bid farewell. The old Theunissen Stadium, which hosted its last season in 2001, was demolished to make room for the Health Professions Building and the College of Medicine, which occupy the site today.