A right-handed hitting outfielder, Hillemann played in the minor leagues for six seasons. Originally drafted by the San Diego Padres in 1987, he played for their farm team in Spokane, Washington. The Spokane Indians won the league championship that season. Hillemann was the top defensive outfielder in the Padres’ organization. In went on to climb the ladder in the San Diego organization, playing for Charleston, South Carolina; Wichita Wranglers in the Texas League and the AAA Las Vegas Stars. In 1992, Hillemann moved to the Milwaukee Brewers’ AAA Denver Zephyrs and the AA El Paso Diablos.

During the 1980s, Charlie was a standout outfielder for St Charles High School, leading the Gateway Athletic Conference in hitting with a .492 average. He was also solid for the St. Charles American Legion team.

He developed into a star player with Southern Illinois University – Carbondale from 1984-87. He was drafted by the Padres after his junior season. In three seasons with the Salukis, Hillemann posted a composite batting average of .316. He is a lifetime member of the Association of Professional Baseball Players.

In addition to baseball, Hillemann was an all-state running back for St. Charles High, leading the team to the Class 4A football state semifinals in 1983.