But that's not why they lost Sunday to the San Francisco Giants. The problem, instead, was a fastball down the middle to Shea Hillenbrand.
Barry Bonds hit his 729th career home run, Omar Vizquel drove in three runs with two triples and Hillenbrand hit a two-run homer to power the Giants to a 7-4 victory over the injury-riddled Cubs and a series win.
Cubs starter Angel Guzman had to exit early because of cramps in his right arm but is not expected to miss a start. The rookie had a 3-1 lead in the fifth and was one out shy of qualifying for the win when he was pulled. The right-hander had fallen behind Steve Finley, 3-0, in the count with two out and one on. Cubs manager Dusty Baker, pitching coach Larry Rothschild and assistant trainer Ed Halbur went to the mound after Guzman was seen flexing his right arm.
Guzman threw a couple warmup pitches, and stayed. He then walked Finley, threw one pitch to Vizquel, a ball, and head trainer Mark O'Neal went to the mound with Baker. Guzman then exited.
"I had this problem twice in Triple-A," Guzman said. "I've been drinking water and Gatorade and that kind of stuff. [Team orthopedist] Dr. [Stephen] Gryzlo said it's normal. The intensity I was using in the game -- cramps happen."
Vizquel greeted Michael Wuertz (1-1) with a triple to right, driving in both runners to tie the game at 3. Hillenbrand followed with his seventh home run to put the Giants ahead, 5-3. That hurt the most.
"It was a fastball up in the zone," Wuertz said. "I left it right over the middle of the plate. I'd thrown three sliders to Omar. Maybe I was trying to outguess myself. If you don't execute a pitch, that's what happens."
Before the game, the Cubs placed catcher Michael Barrett on the 15-day disabled list, the 19th time they've used the DL, which is a team record. Jacque Jones had to leave Sunday's game after eight innings because of an infected tear duct in his left eye. His status was day-to-day. Guzman should be able to make his next start Friday in Atlanta.
"He's OK," Baker said. "He was throwing the ball good and needed one more out to try to get his first victory. He couldn't go any longer. It's nothing structural. We just have to find out why he cramps.
"This happened at the wrong time," Baker said. "In the game, it boiled down to a walk at the wrong time and a big ol' two-run home run. Wuertz had him swinging at those sliders in the dirt and was trying to throw a fastball up and away, and it went right down the heart of the plate."
The Cubs made another baserunning mistake in the eighth. Henry Blanco was at second and Ronny Cedeno at first with two out, and both broke on a pitch in the dirt to Angel Pagan. Giants catcher Eliezer Alfonzo recovered the ball in time to throw Cedeno out at second.
"It was very disheartening," Baker said of the play. "Young guys are trying to hustle and make things happen. In that situation, the runner on first has to wait longer than the runner on second to see if he goes. It was a good play by Alfonzo to get the trail runner, because he saw he couldn't get Henry. In that situation, you have to know you're going to make it."
Speaking of Henry, Blanco was making his first start at first base because the Cubs were shorthanded. Derrek Lee didn't start as he continues to build up strength in his right wrist. Blanco did OK.
"I didn't have to make a diving catch or anything like that," he said. "I did what they asked me to do and hopefully, I'll get back there one day."
He did borrow Lee's glove for the game, and gave it back.
"I couldn't miss anything with that," Blanco said.
Bonds didn't miss in the eighth when he led off with his 21st homer of the season, connecting against Les Walrond. He's now 26 shy of tying Hank Aaron for first on the all-time home run list. Jason Schmidt (11-7) picked up the win, striking out five and giving up three runs on eight hits over seven innings.
Guzman is still waiting for that first "W."
"That's the sad part of today for me," he said. "I was helping my team pretty good and making my pitches, and that's the sad part."
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.