Caridad said he felt some discomfort on Monday. He most likely doesn't need the full time on the disabled list, but the Cubs want to make sure Caridad has enough time to recover.
"This time of year, we'll do what's best for the long-term picture and the players' health," general manager Jim Hendry said.
Gray, acquired from the Athletics for Jake Fox and Aaron Miles, had thrown four scoreless innings over three games for the Iowa Cubs, giving up one hit. He missed most of Spring Training because of a groin injury suffered before camp opened. Gray may get some razzing from the fans at Wrigley Field because he's wearing No. 34, which hasn't been worn since Kerry Wood pitched for the team.
"I'll use [Gray] the way I use the rest of these guys," manager Lou Piniella said. "Get him in there and let him pitch. We have a little sorting out to do with our bullpen and we're in the process of doing that."
The Cubs came into the season projecting Caridad as the leading setup pitcher. Now, Piniella said he will call on pitchers based on the best matchup, but also rely on lefties John Grabow and Sean Marshall.
"The right-handers, we'll give them all opportunities," Piniella said. "The more experience and more success these younger pitchers can get under not-duress situations, the better they'll be for it."
Gray was eager to get going.
"I didn't know how well I'd injured myself," he said of his spring. "It feels good now, and hopefully I can help the team out a lot."
One other pitcher eager to chip in is Jeff Samardzija, who rebounded from a tough outing on Opening Day when he walked three and gave up two hits over one-third of an inning. On Monday in the Cubs' home opener, he retired the side.
"It was a long week [between outings], and a lot goes through your head," Samardzija said, "but that's part of it."
His goal after the Opening Day mess was to get into a rhythm quicker on the mound, and he did that on Monday.
"I'm a very mental guy and I like to think about what happened and really break things down, so to sit and think about it for four, five, six days probably wasn't the best situation ever. I'm very critical of myself, but I learned from it. I just like to pitch."
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.