The move leaves the Cubs with two catchers -- rookie Kyle Schwarber and Miguel Montero, who was activated from the disabled list Friday.
Szczur, who was optioned to Iowa to make room for Montero, was recalled for the sixth time this season. He entered Saturday batting .217 in 60 at-bats this season with eight RBIs and one home run.
• Addison Russell has always wanted to play shortstop in the big leagues, and the Cubs rookie is getting his chance.
Russell, who has started 84 games at second base, made his seventh start at shortstop Saturday, moving to the other side of the infield to replace Starlin Castro, who has been benched indefinitely.
"I've been playing that position since I was a little kid," Russell said of shortstop. "Finally my dreams are coming true. But I just want to help the team. They'll put me where they need me, and I'll try to get the job done."
Playing so much second base has helped the 21-year-old understand what he needs to do at shortstop as well.
"I know the tendencies of second base now, so I can get a better feel for shortstop," Russell said. "They're two completely different jobs. I like short, I like second."
Russell didn't know exactly why he was moved, something manager Joe Maddon did to get Schwarber in the mix and generate more offense.
"I don't know what's going on," Russell said. "[Castro] has always been a good teammate and he picks me up whenever I'm down."
• Maddon said they're working with right fielder Jorge Soler on his defensive play and to forget bad at-bats when he's in the field.
"It's just the way a guy's motor runs," Maddon said. "I've had really good players and when they're hitting well, the motor is fine, and when they're not hitting well, the motor becomes a concern. We're trying to get [Soler] to understand that even when things aren't going well, to stay in that higher gear."