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3/22/2014 4:21 P.M. ET

Starlin gets at-bats in Minor League camp

MESA, Ariz. -- Cubs shortstop Starlin Castro got his first at-bats since he injured his right hamstring, going to Minor League camp for four to six at-bats on Saturday.

Castro, who sustained a strained right hamstring on March 2 stealing second base, was used as a designated hitter in the game, and didn't run the bases hard. His baserunning drills were scheduled for after the game.

"I just need at-bats," Castro said.

Cubs manager Rick Renteria said Castro would get four to six at-bats in the Minors on Sunday as well, and the next step could be a Cactus League game. There is one week remaining before Opening Day on March 31.

"Let's see today how it goes," Castro said.

Renteria said there is enough time for the shortstop to be ready by Opening Day.

"I think it's a great sign," Renteria said of Castro being able to hit this weekend.

Last spring, the shortstop strained his left hamstring and only missed two weeks. The difference this March is that there was more fluid in his right hamstring and more inflammation.

"I feel good, not any pain or anything," Castro said. "Let's see today after the game. I'll do full baserunning [after the game] -- let's see how I feel."

Baez lauded for progress, takes roster move in stride

MESA, Ariz. -- Javier Baez reported on Saturday feeling much better after having to come out of Friday's game with a sore right heel, injured because of some bad cleats and a misstep at first. Then, the Cubs' top prospect got the news that he was being assigned to the Minor Leagues.

Baez was one of seven players trimmed from the Cubs' big league spring camp on Saturday. Manager Rick Renteria said he was impressed by the shortstop, who ranked among the Cactus League leaders in home runs with five, and was batting .310 in 14 games. Baez led the Cubs in at-bats with 42 heading into Saturday's game.

"I think he's made a lot of progress," Renteria said. "One of the things we talked about is to make sure he continues to work on his defense, continue to go down there and put together some good at-bats, try to get on base a little more through the process and just go out there and be a professional.

"He's been hustling and busting his rear end out here this spring and he's looked good."

Baez said he wasn't disappointed.

"Not really," he said. "There are a lot of people here, veteran guys, so I understand.

"I'm just going to go over there and play the game like I've been doing, play hard every day."

The good news is Baez wasn't hurt after Friday's freak step. With one out in the sixth and the Cubs leading 4-0 against the White Sox, Baez hit a grounder to shortstop Alexei Ramirez. Baez beat the throw but stepped awkwardly on first base and appeared to slip with his right foot.

"It's happened before," Baez said. "I can't wear [metal] cleats. I reached for the bag and I felt it a little bit on my heel. I could've kept playing but it was my last at-bat anyways so they took me out of the game."

He has no problem with rubber cleats but was wearing the metal ones because of the wet surface in Glendale.

"If I wear cleats, I just have to cut the back cleat and I'll be all right," Baez said. "When I hit the ground hard with all my weight, it hurts."

He said his shoe "pinched" his heel but the pain was gone quickly. He sustained a right heel contusion.

"It bothered me for a couple minutes and it was gone," he said. "It's happened before."

Renteria said the 21-year-old infielder took the news of his assignment to the Minors well.

"He took everything I mentioned to heart and will try to continue to improve and try to become the best player he can possibly be and get ready," Renteria said.

The Cubs want Baez to work on his defense, and he knows it.

"I talked to them about that, and I just have to try to make my throws to first base from short," Baez said. "A lot of times, my hand is sweating, and I'm like kind of scared to throw over. This year, I've been doing pretty good."

Part of being more comfortable includes knowing the runner, knowing how hard the ball is hit. There's not much he can do about sweaty hands.

"Sometimes I'd be in the field, and my hand would be sweating and maybe I'm not thinking about what I have to do with the ball if it's hit to me, or something like that," he said. "Sometimes I get a little bit nervous. It's all part of the game."

It's all part of the process.

Valbuena drawing attention in hunt for third-base job

MESA, Ariz. -- Luis Valbuena is just focusing on what he can do, and hopes it's good enough to earn him the starting third-base job on Opening Day for the Cubs.

Valbuena hit two home runs on Friday in the Cubs' 7-0 win over the White Sox and was batting .276 over 11 Cactus League games. The Cubs still have Donnie Murphy and Mike Olt in camp. Olt made his second spring start at third on Saturday and has gotten a lot of attention.

"I'll be ready for everything," Valbuena said Saturday. "I can't make the decision. I'll do whatever I can in the field. I'll work second, short, third. I'm ready for anything. Wherever they need to put me to play, I'll be there."

He played second base all winter in Venezuela, and said that he's actually more comfortable there. The Cubs are still sorting out their infield, trying to decide if Olt is ready to play on a regular basis.

Valbuena, who hit 12 home runs and batted .218 last season with the Cubs, didn't show up this year feeling he had anything locked up.

"Every time I go to camp, I don't feel comfortable," Valbuena said. "I compete every time. Every time they give me an opportunity and put me in the game, I'm fighting for my job."

What more can he do?

"I'm not trying to do too much," he said. "I play my game. I play like I know I can. Every day when I come here, I do the best I can and I don't try to hit home runs. I just try to make good contact. If I make good contact, the ball will go. I never go up there and say, 'I want to hit a home run.' Every time I go to to hit, I'm focused on getting good contact every time."

Cubs still have options for fifth rotation spot

MESA, Ariz. -- Travis Wood will start the Cubs' home opener on April 4, manager Rick Renteria announced Saturday. The team is still trying to fill the fifth spot in the rotation.

"It'll be exciting for sure, even though Pittsburgh is a great place to pitch," said Wood, who had been expected to follow Jeff Samardzija in the rotation.

Isn't Wrigley Field a good place?

"Wrigley's fine," Wood said, laughing. "It'll be cold either place, so it's not like the weather will be different. The place will be packed, it'll be jumping, it'll be nice."

Renteria said they made the decision because of matchups. Wood has made three starts against the Phillies, the Cubs' opponent for their home opener, and held them to five runs on 13 hits over 21 1/3 innings.

"I had a pretty good track record against them and hopefully I can keep it going and start the season off right," Wood said.

Samardzija will make his second consecutive Opening Day start March 31 against the Pirates, and be followed by Edwin Jackson, Jason Hammel and then Wood. The Cubs' options for the fifth spot include Carlos Villanueva, Chris Rusin and Tsuyoshi Wada. Villanueva, a valuable swingman, will start Monday against the Padres, while Wada will start Tuesday against the Angels.

Rusin, who threw five shutout innings on Friday against the White Sox, is a possibility, but the Cubs may pick Villanueva because of his versatility and the fact they have four off days in the first three weeks of games. If the other four starters stay on a five-day rotation, Villanueva could slide into the bullpen until needed.

Renteria didn't tip his hand on Saturday when asked about the fifth spot.

"They're all still in the mix," he said. "They're all going out there and doing a nice job."

The Cubs had projected Jake Arrieta as the fifth starter, but he's been slowed this spring because of tightness in his right shoulder. On Sunday, Arrieta was scheduled to throw a bullpen.

"I'm hoping the next step is a game," he said Saturday. "We'll talk things over and see where we stand."

So far, he's had no problems with his shoulder, throwing 75 pitches in a sim game on Friday.

"The progression and routine is going well," Arrieta said. "My body feels well, shoulder feels good. The velocity and arm strength is right where it needs to be."

Cubs fans will get a chance to see two of the top pitching prospects on Tuesday when C.J. Edwards and Eric Jokisch pitch against the Padres. Edwards, 22, was a combined 8-2 with a 1.86 ERA in 24 games with Class A Hickory and Daytona last season. The Cubs acquired him in the Matt Garza deal. Jokisch, 24, was 11-13 with a 3.42 ERA at Double-A Tennessee in 2013.

Baez, Parker among Cubs' roster cuts

MESA, Ariz. -- The Cubs trimmed seven players from big league spring camp, including top prospect Javier Baez and pitcher Blake Parker.

Parker was optioned to Triple-A Iowa, and infielders Baez and Chris Valaika, outfielder Casper Wells, and pitchers Brian Schlitter, Jonathan Sanchez and Chang-Yong Lim were assigned to the Minor League camp. The moves reduce the spring camp roster to 37.

Baez batted .310 with five home runs and five RBIs in 14 Cactus League games with the Cubs this spring, and ranked among the Major League spring leaders in home runs. He is projected as Triple-A Iowa's starting shortstop.

Parker, 28, who spent nearly all of last season in the big leagues after posting a 1.17 ERA in eight games in Spring Training, has given up six runs over six innings in six Cactus League games this year.

"He obviously did a nice job last year, and he's got to continue to command the zone and not make things too complicated and do what he does," Cubs manager Rick Renteria said. "He's got a tremendous arm."

Wells has been sidelined with back problems, and he underwent an MRI this week. Sanchez, 28, who threw a no-hitter with the Giants, was a non-roster invitee.

Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.