He was a relief pitcher and shortstop who played in the farm system of the Cleveland Indians from 1978 to 1980. In 1978 and 1979, he pitched for the Waterloo Indians in Waterloo, Iowa. In 1978, he also played for the Batavia Trojans in Batavia, New York. In 1980, he was on the Chattanooga Lookouts in the Southern League.

Warnecke was playing for the McKendree University Bearcats in 1978 when he was drafted by the Cleveland Indians. He was the first McKendree baseball player ever selected in the Major League draft. He was a four-year starter on the Bearcats team from 1975 to 1978. His career batting average at McKendree was .348, including a career-best .396 as a junior. He was a dominant force on the mound, cementing his status as one of the top pitchers in the league.  Warnecke was the Most Valuable Player on the Bearcats team in 1978. That year, he was named to the All-State and All-District teams. He was also selected to the Missouri-Illinois Collegiate League all-star team. From 1980 to 1984, he
played for the renowned Aviston Aces in the Clinton County League. He is in the Clinton County League Hall of Fame.

In the early 1970s, Warnecke pitched for Central High School in Breese, Illinois. He is in the Central High School Hall of Fame.In the 1990s, he coached youth baseball teams in his hometown of Aviston, Illinois.