Because the Cubs' orthopedic specialist, Dr. Stephen Gryzlo, is in Chicago and Prior has seen Yocum before, the team decided to send the pitcher west. Cubs pitching coach Larry Rothschild said Prior halted his scheduled side session before he got on the mound Tuesday.
"We started long tossing and working our way towards the mound and it wasn't getting loose, so we weren't going to try it," Rothschild said.
The Cubs did not know if Prior would need an MRI, and wanted to wait until Yocum had a chance to do an examination.
"You hope it's just a minor setback," Cubs manager Dusty Baker said. "We have to stay positive and keep our fingers crossed."
It's going to be tough for Prior to stay positive. He was slowed last spring by an elbow injury and the year before by a leg problem. He's been on the disabled list every year he's been in the big leagues since his rookie season in 2002. In 2005, he made 27 starts and went 11-7 with a 3.67 ERA.
"I talked to him. He's tired of it, too," Baker said. "You could tell he was a little distraught about the whole thing. He wants to pitch. He wants to pitch with nothing wrong."
Earlier this spring, the Cubs had to deal with rumors that Prior had either shoulder or elbow problems, and that was why he had yet to appear in a Cactus League game. Prior was to throw his second simulated game on Thursday and was in line for his first spring start. All of that is now delayed.
"It's unfortunate," Cubs general manager Jim Hendry said. "The first time he's ever complained of discomfort since we got here [in spring camp] is today. It will be perceived any way people want to perceive it. There's no advantage to us holding back until March 14 and then discussing a problem that we knew about earlier.
"Hopefully, it's just a little snag and he's back with a few days setback and he's back on his program at the end of the week," Hendry said. "Today was the first day that he ever told [O'Neal] or Larry that he had discomfort."
O'Neal said Prior had been treated for normal soreness that every pitcher goes through.
"There haven't been any setbacks in any of his throwing," O'Neal said. "Anything that's been asked of him, he's been able to meet. It was unfortunate today that he started having this."
Hendry said he was surprised when O'Neal called him about 45 minutes before Tuesday's game against the Seattle Mariners with the news.
"The sim game [on Sunday, when Prior threw 35 pitches] went well," Hendry said. "We thought he'd be doing four innings on Thursday. I was looking at at least three [Cactus League] starts. Hopefully it's just a little snag. When he said he had discomfort, it's the first time he had that all spring.
"We're certainly at the point where we're not going to take any chances," Hendry said. "He's had a zero complaint camp. When he said he had a little snag today, there's no sense of him coming out on Thursday."
Asked if the soreness was normal, Rothschild said no.
"I would say it seems like it's a little more than that," he said. "If [it were normal], we'd go a day and see how it is tomorrow. We won't know until he gets checked out."
No one is sure what the next step is in Prior's program. He was tentatively scheduled to start the second game of the regular season on April 5 against Cincinnati.
"I'm going to wait and see what we're dealing with first and try to figure out what we have to do and go from there," Rothschild said. "Everybody knows what he means to the team. We'll have to wait and see."