In his first season of professional baseball, Zdeb was assigned to the rookie leagueBillings Mustangs, where he batted.184. He also spent 1972 in rookie ball with the Kingsport Royals, where he improved to a.319 batting average with 12 home runs. In 1973, he began the year at Waterloo in the Midwest League, where he hit.355, earning him a promotion to the high-A San Jose Bees, where he struggled, hitting.195. In 1974, Zdeb returned to San Jose. In his first full season there, he batted.295. Over the next two seasons, he continued to move up the ladder, playing at Double-A Jacksonville in 1975 and AAAOmaha in 1976.
"Long hair" confrontation
At some point, during minor league spring training, he showed up to camp with long hair, which was against team policy. Manager Joe Gordon refused to give him a uniform, so he approached general managerLou Gorman, asking "Mr. Gorman, if I cut my hair, will I become a better ballplayer?" Gorman said he needed to cut it to properly represent the organization, and after initially refusing, he did so a couple days later.
Major leagues
Rookie season: 1977
After the 1976 season, the Royals traded their primary backup outfielder, Jim Wohlford, to the Milwaukee Brewers, opening up a spot for Zdeb. With the left-handed Dave Roberts on the mound for the Detroit Tigers on Opening Day, the right-handed hitting Zdeb wound up starting in left field in place of the left-handed hitting Tom Poquette. Zdeb went 1-for-4 with a run scored in his major league debut. Zdeb and Poquette platooned over the rest of the season, and the rookie finished with what turned out to be a career high.297 batting average in 105 games. He also had career bests with 2 home runs and 23 RBI. In the 1977 American League Championship Series against the New York Yankees, Zdeb appeared in four of the five games, but failed to get a hit in nine at bats, although he did steal a base.
Remaining Royals career
In 1978, Zdeb saw his playing time reduced with the arrival of Willie Wilson, and even wound up back in the minors briefly. With three players sharing left field, Zdeb wound up appearing in just 60 games. His batting average fell to.252, without a home run and with just 11 RBI. With Wilson named the full-time starter in left field for the 1979 season, Zdeb found himself in strictly a reserve role to start the season. After 15 games in which he batted just.174, Zdeb was sent down to the minor leagues. However, he also struggled in Omaha, batting just.224, and was not given a September call-up.