Chicago's starting pitchers have been unable to go five innings in the past two starts, and Eyre will be sidelined at least seven more days, so a fresh arm was needed. The lefty was placed on the 15-day DL, retroactive to Friday, due to a strained left groin.
With Eyre sidelined, the Cubs will have one left-hander, Neal Cotts, in the bullpen.
"It's better than none," Cubs manager Lou Piniella said. "A groin is a delicate component for a pitcher."
Plus, the injury is to Eyre's left side, which is his pushoff side, and that leg needs to be strong.
Theriot did not start for the second straight game Saturday to give his right hand more time to heal. His hand was bruised and there was some swelling. How did he injure it?
"How did he do it? I'd prefer not to say," Piniella said.
Mark DeRosa was joking with Theriot before Saturday's game, saying the shortstop had jammed his hand.
"If he said it, then I'll concur," Piniella said.
All Theriot would say was that his hand was "fine," and that he did expect to play Saturday.
"He's sitting on his average," DeRosa said, jokingly. "He's trying to make his first All-Star Game."
Asked if he did jam his hand, Theriot said no, but that it was a little sore.
Moving on, Carlos Zambrano threw off flat ground Saturday and will have a bullpen session on Sunday. He is on the disabled list because of a strained shoulder, and if all goes well, the righty will open the Cubs' series at St. Louis next Friday.
"I feel good today," Zambrano said Saturday. "I played catch today, and tomorrow I'll throw on the side and talk about it."
Alfonso Soriano rejoined the Cubs on Saturday and said he was encouraged by the X-rays taken Friday that showed his hand was progressing well. He has a broken bone in his left hand, suffered when he was hit by a pitch June 11.
"[Friday], I got very good news," Soriano said. "They told me they want to do something this week on the road, so I hope I can do something with my hands, because I don't have anything to do and I'm very bored right now."
He has no pain, but said his hand felt a little weak.
Outfielder Reed Johnson, who has been out because of back spasms, took batting practice for the second straight day Saturday and should be activated on Thursday.
The Cubs have to deal with the aches and pains.
"We just have to live through it," Piniella said of this stretch. "We have to tough it out and win as many games as we can until we're healthy again. I told you we were in for a rough stretch and we were winning games and concealing some things. Now we just have to tough it out.
"When you're winning, you tend to overlook things. We've been struggling and some deficiencies have showed up, and now we have to tough it out. Hopefully, we get a little better pitching and, at the same time, swing the bats better and hopefully we can win some ballgames until we get better."
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.