Szczur was hitting .295 with seven home runs, 26 RBIs and 19 stolen bases in 58 games with Iowa. In 32 games with the Cubs earlier this season, he batted .211 with one homer, eight RBIs and two steals.
Richard was 2-0 with a 4.29 ERA in four games, including three starts.
Right-hander Dan Haren, acquired last Friday from the Miami Marlins in a trade, will take Richard’s spot in the rotation and make his Cubs’ debut Wednesday night against the Pirates.