Acquired in a 1959 trade with the Philadelphia Eagles after an earlier stint in Baltimore, Bill Koman entered the Cardinals organization with little fanfare. What the franchise received in return was the physical heartbeat of their defense for nearly a decade. Sliding in at outside linebacker, the University of North Carolina product spent nine seasons with the Big Red (1959–1967), establishing a standard of hitting and durability that set the defensive tone throughout the 1960s.

Koman was an aggressive, downhill defender who relied on raw power, violent shed-and-tackle mechanics, and exceptional durability. Operating through bad knees that required constant wrap and treatment, Koman rarely missed action; he played in 120 consecutive regular-season games for the Cardinals, missing just a single contest over his nine-year tenure with the team.

Following the team’s move from Chicago to St. Louis in 1960, Koman's relentless tackling earned him widespread recognition. He reached his individual peak during the 1962 season, earning his first Pro Bowl invitation after recording 3.5 sacks, two interceptions, and three fumble recoveries.

He repeated that elite standard in 1964, garnering a second Pro Bowl selection as the operational leader of an aggressive front seven. In 1965, he was awarded the Old Pro Award by the St. Louis Quarterback Club, cementing his status as one of the most respected figures in the locker room. Battling through constant knee issues, Koman suited up for 120 consecutive games for the Cardinals, missing only one game across his entire nine-year run with the organization.

Koman retired following the 1967 season. In a Cardinals uniform, he appeared in 121 games, making 121 starts, while accumulating 24.5 unofficial sacks, 6 interceptions, and 16 fumble recoveries.