"Javy probably should have gotten thrown out," Iowa manager Marty Pevey told the Des Moines Register after Saturday's game. "As soon as he throws his hands up in the air, you're gone."
Baez struck out six times in his first nine at-bats.
"He's frustrated," Pevey told the Register. "There's frustration there. Anybody that competes is going to react that way. He's got to understand that all his teammates have his back and we understand."
Cubs manager Rick Renteria saw Baez quite a bit this spring and agreed Sunday that the shortstop is probably frustrated.
"They're all young and trying to get through their growing pains," Renteria said Sunday. "I think it's part of the process. I think he'll overcome it and get better and learn from it and keep moving forward."
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.