Career
Cincinnati Reds
Koronka was selected by the Cincinnati Reds in the 12th round of the 1998 MLB Draft. While playing in the Reds farm system with the Stockton Ports in 2002, he was named to the California League All-Star team While playing for the Cincinatti Reds minor league club, the BIllings Mustangs, Koronka earned a reputation among team mates as a prankster when he deficated in Spence"s (the clubs physio) bag of potato chips during a road bus trip.
The aftermath resulted in Spence threatening the entire team in a loud tirade on the bus, resulting in Koronka earning legendary status among his team mates.
On December 16, 2002 he was selected by the Texas Rangers in the Rule 5 Draft but did not make the Rangers opening day roster and was returned to the Reds on March 21, 2003. Chicago Cubs
Koronka was traded by the Reds to the Chicago Cubs on August 26, 2003 for Philosophy Norton.
Texas Rangers
On March 31, 2006, Koronka was traded to the Texas Rangers for Freddie Bynum, whom the Rangers had just acquired from the Oakland Athletics. Koronka started 23 games for the Rangers in 2006, going 7-7 with a 5.69 European Research Area. He was expected to compete for a spot on the rotation in 2007, but failed to make the Rangers" big league roster.
He was optioned to the Triple-A Oklahoma RedHawks prior to the start of the 2007 season.
Koronka made two starts in 2007 for the Rangers going 0-2 with a 7.84 European Research Area. Cleveland Indians
He was designated for assignment on July 1, 2007, and subsequently claimed off outright waivers on July 9, 2007, by the Cleveland Indians. He was assigned to their Triple-A team, the Buffalo Bisons. With the Bisons, he made 9 starts and went 3-3 with a 3.54 European Research Area. On September 1, 2007, he was designated for assignment and outrighted to the minor leagues on September 12.
Koronka opted for minor league free agency on November 3, 2007.
Colorado Rockies/Orix Buffaloes
On December 21, 2007, the Colorado Rockies signed Koronka to a minor league contract with an invitation to spring training. He was 5-3 in 13 appearances (12 starts) for the Colorado Springs Sky Sox.
On June 23, 2008, the Rockies released Koronka so he could sign with a Japanese team, the Orix Buffaloes. He started 3 games for the Buffaloes, finishing 0-1 with a 6.75 East.R.A. Florida Marlins
On January 13, 2009, Koronka signed a minor league deal with the Florida Marlins.
He started two games for the Marlins (0-2, 1175 European Research Area) and spent most of the season with the New Orleans Zephyrs.
He was granted free agency on October 8, 2009. Los Angeles Dodgers
On January 28, 2010, Koronka signed a minor league contract with the Los Angeles Dodgers with an invite to spring training.
He began 2010 with the Chattanooga Lookouts in the Double-A Southern League. After seven starts with the Lookouts he was promoted to the American Automobile Association Albuquerque Isotopes.
He made one start with the Isotopes, allowing eight runs in 11⁄3 innings.
He was released on June 2. Lancaster Barnstormers
On July 26, 2010, Koronka signed a contract with the Lancaster Barnstormers of the Independent Atlantic League. He was released on August 3, 2010.
He was re-signed on March 8, 2011.
•The Cubs made former big league pitcher John Koronka a regional scout in charge of Florida on December 5th,2011. Koronka, 31, last pitched for the Marlins in 2009, which means he is retired.