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6/29/2013 3:10 A.M. ET

Castro improving after one-day breather

SEATTLE -- Since his one-day breather, Cubs shortstop Starlin Castro is 4-for-14, which is encouraging. Has manager Dale Sveum seen changes since Tuesday's day off, Castro's first of the year?

"Maybe a little attitude change," Sveum said Friday. "I think the mechanics of his swing are probably the same. He's mixed in some hits, which are nice. That's usually what gets you going sometimes.

"He's still struggling a little bit with the fastball," Sveum said of Castro, who is batting .231. "The mechanics are the same. Hopefully, he keeps gradually understanding what he has to do."

Castro began the season with a career .297 average, and is batting .153 in June after Friday's 0-for-4 performance.

Soriano to handle DH duties in Interleague Play

SEATTLE -- Alfonso Soriano was the designated hitter for Friday's Interleague game in Seattle and will likely handle that role in the Cubs' six-game West Coast swing against the Mariners and Athletics.

Soriano's first game at DH was a success, as the veteran slugger went 2-for-4 with a home run off Hisashi Iwakuma in the Cubs' 5-4 loss on Friday.

Ryan Sweeney and Brian Bogusevic will be getting the action in the outfield for the Cubs with Soriano serving as the DH. The Cubs will have to figure out how to get everyone at-bats when David DeJesus returns from a sprained right shoulder. DeJesus was in Chicago, continuing his rehab.

"A couple of them might be part of our future, left-handed hitters who are better athletes, two-way players," manager Dale Sveum said of Sweeney and Bogusevic. "We'll work it out to figure out the playing time."

Sveum will talk to Soriano about playing time if there's a significant change for the 37-year-old outfielder.

"You're not going to just do something like that to a guy who's had that kind of career," Sveum said. "I'll have to figure out how to get these guys their at-bats with matchups, or whoever's the hottest. A lot of times those things work themselves out."

Extra bases

• Dioner Navarro has caught Matt Garza's last three starts, and the right-hander gave up two earned runs in those games, but Cubs manager Dale Sveum said Navarro isn't the pitcher's personal catcher.

"It's just how it all works out sometimes," Sveum said Friday. "[Welington Castillo] has caught them all and everybody has had really good games. If you have that kind of fastball command -- [on Thursday], Garza had his slider and his command. When you have that kind of outing, it doesn't matter what's going on behind the plate."

Castillo is the Cubs' regular catcher, and has started 57 games compared to Navarro's 21.

• Scott Baker, rehabbing from Tommy John surgery, will throw his second simulated game on Saturday in Mesa, Ariz. His first outing lasted 20 pitches and went well.

"Everything went good and the velocity was up there," Sveum said of Baker. "We hope he keeps going in the right direction."

The right-hander could be pitching for the Cubs by late August.

"He's basically starting his Spring Training right now," Sveum said. "The first day pitchers throw live, it's basically like that [for Baker]."

• Steve Clevenger, sidelined since April 14 with a left oblique strain, was activated from the 60-day disabled list and optioned to Triple-A Iowa. To make room on the 40-man roster, pitcher Zach Putnam (bone spur) was transferred to the 60-day DL.

• Outfielder John Andreoli was promoted from Class A Daytona to Double-A Tennessee, while Bijan Rademacher was promoted from Class A Kane County to Daytona on Friday. Andreoli was batting .318 at Daytona.

• On Saturday, the Cubs and Mariners will "Turn Back the Clock" and wear uniforms from 1909. The Mariners didn't exist then, but there was a Minor League team in Seattle called the Turks. The '09 Cubs were managed by Frank Chance and went 104-49, but finished second that year.

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.