The Chicago Cubs sent pitcher Jon Leicester back to Triple-A Iowa Wednesday while calling up John Koronka to take his place on the roster. Koronka, 24, looks to make his major league debut. In 10 games (nine starts) for Iowa, he is 4-5 with a 4.73 ERA. Leicester, who was in his third stint with the Cubs, has seen action in six games (one start), but did not make an appearance since being recalled May 29.