PHILADELPHIA -- Cubs right-hander Carlos Zambrano will throw a simulated game on Monday in an effort to ramp up his stamina for a return to Chicago's rotation.

Manager Lou Piniella said he will have Zambrano throw 60-70 pitches during the team's off-day Monday and see how the converted reliever feels. Zambrano has made eight appearances as a setup man since April 22, but the team announced on Tuesday that it is planning to move him back to the starting rotation.

On Wednesday, Piniella clarified the next few steps of that process.

"We'll give him a little work between now and Sunday," Piniella said. "If we can stretch him out, we'll do that; if not, we'll use him in the bullpen. Monday, we'll throw a nice simulated game. It's a day off, he can throw 60-70 pitches, and then we'll see how he feels after that. We'll see if he needs one more good work day in a game or if he's ready. We'll make that determination next week."

Zambrano has a 6.23 ERA as a reliever and a 7.45 ERA in four starts this season. The Cubs placed him in a setup role in an effort to boost the 6-foot-5, 260-pound right-hander's sagging velocity. So far, the results have been mixed.

But Piniella was pleased with Zambrano's appearance in the ninth inning of Chicago's 6-2 win over Colorado on Tuesday, in which he threw a scoreless inning with two strikeouts.

"If he goes out there in the rotation and throws the ball like he did last night, it's going to be a good situation for both Carlos and for us," Piniella said.

Caridad returns to DL; Stevens called up

PHILADELPHIA -- Cubs right-hander Esmailin Caridad was placed back on the 15-day disabled list with a right elbow strain Wednesday. Reliever Jeff Stevens was called up from Triple-A Iowa to replace him.

Caridad complained of soreness in his elbow after Tuesday's game against Colorado, in which he pitched and faced one batter (walk).

"The decision was made to DL him, see the doctor today and see exactly what the problem was," manager Lou Piniella said. "We'll act accordingly."

Caridad was just activated off the DL on May 8 after missing nearly a month with a right forearm strain. He had allowed one earned run in his last four appearances.

Stevens, a 26-year-old right-hander, had a 2.60 ERA in 12 games for Iowa.

"They say that this young man's slider has gotten a lot better and he's been throwing the ball well," Piniella said of Stevens, who is active for Wednesday's game.

Baker trots out to right field

PHILADELPHIA -- Before Tuesday's game against Colorado, Cubs manager Lou Piniella stopped Jeff Baker to let him know he'd be in the lineup on Wednesday against Philadelphia.

Piniella didn't know where Baker would be in the lineup, but he promised the reserve infielder he'd be getting some playing time.

Baker arrived at Citizens Bank Park to see his name slotted to play right field, a position he has not played since 2008 with Colorado. He's played a total of 34 games in the outfield in his career.

"I'll just try and catch it and hit the cutoff man," Baker joked.

When young shorstop Starlin Castro was called up on May 7, he pushed Ryan Theriot over to second base and infielders Mike Fontenot and Baker were left searching for opportunities. Baker last started on May 12 at third base.

"I'm trying to get all these guys at-bats," Pinella said. "It sounds easy, but it's not the easiest thing in the world."