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05/12/2013 6:52 PM ET

Duke determined to improve on recent struggles

WASHINGTON -- Nationals reliever Zach Duke endured his second consecutive rough outing on Saturday, continuing what has been a trying season. The left-hander, filling a long-relief role, has not worked frequently, but when he has, he often has struggled.

"I'm not commanding the ball, working behind in the count, and then throwing the ball down the middle," Duke said. "That's what it all boils down to."

The 30-year-old has tossed 15 innings over nine appearances, surrendering 22 hits and compiling an 8.40 ERA. On Saturday, he gave up four runs in two-thirds of an inning.

That appearance came nearly two weeks after Duke's previous one, when he gave up three runs in three innings on April 30 at Atlanta. He admitted that the infrequent work is a factor, but he said it's something he has to overcome.

"It's tough. I haven't done this role before, but at the same time I'm a professional and I should be better than that," Duke said. "I expect more of myself. I can't do that to this team."

The Nationals signed Duke to a one-year, $700,000 Major League deal this offseason after he made eight solid relief appearances for the club last September. The former Pirates starter had gone 15-5 with a 3.51 ERA in 26 starts for Triple-A Syracuse before his recall.

But Duke -- the only lefty in the Nationals' bullpen -- has struggled to get going since his season debut, when the Reds reached him for six runs -- five earned -- in 2 2/3 innings on April 5. Now he's working on drills to try to find a consistent rhythm and release point, as well as stay sharp between outings.

"I'm realistic," Duke said. "I know this game's all about results, and I'm prepared to do the work to get better results."

Zimmerman shows support with pink bat, cleats

WASHINGTON -- Pink bats, shoes, wrist bands and other apparel were commonplace around Major League Baseball on Sunday, and it was no different at Nationals Park. Several Washington players sported various items as part of MLB's celebration of Mother's Day and promotion of breast cancer awareness.

Third baseman Ryan Zimmerman used a pink bat -- as he has done each year since MLB started the tradition in 2006 -- and also wore pink cleats.

Those game-used Louisville Sluggers are auctioned off exclusively on MLB.com to raise money for MLB Charities in support of the fight against breast cancer. Zimmerman also is happy that the effort is tied in with Mother's Day.

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"I think moms get overlooked a lot in sports, so it's nice to be able to do that," Zimmerman said.

His mother, Cheryl Zimmerman, has been battling multiple sclerosis since 1995, and he runs the ziMS Foundation to help find a cure for the disease. Despite her condition, Cheryl has continued to play a major role in her son's life, as so many mothers do.

"They teach you a lot of life lessons along the way and make sure you grow up and do things the right way," Zimmerman said. "Still to this day, I'll have some voice mails or text messages if I say some bad words on camera or something like that. Your mom, whether you're 2 or 32, is always going to look out for you and make sure you do things the right way."

Center fielder Denard Span also sported a pink bat and batting gloves on Sunday and was happy to be able to show his appreciation for his mom, Wanda Wilson.

"Mother's Day in Major League Baseball, I think, is done the right way," Span said. "It's fun to sport the pink -- the pink shoes, the pink bats, the batting gloves. I'm pretty sure every man in this locker room, in this game, a mother played a big part in them being here."

Nationals bench striving to find 2012 form

WASHINGTON -- One of the many reasons the Nationals soared to 98 wins and a division title last season was the play of the bench. The team's pinch-hitters ranked first in the Majors with a .288 average, second with a .367 on-base percentage and second with a .786 OPS while also contributing when called upon to fill in as starters.

The results have not been the same this year.

The sample size is small, but Nationals pinch-hitters entered Sunday just 7-for-47. Combined, they ranked 13th in the National League with a .149 average, 15th with a .200 on-base percentage and 14th with a .413 OPS.

"I have no idea why. Same preparation, same everything, same guys," veteran infielder Chad Tracy said. "You can't guide the ball when you hit it. You can hit balls hard, but if they don't fall or find holes, it shows in the numbers. It looks worse than it probably is."

Tracy is 1-for-12 as a pinch-hitter, although he has seen a few well-struck balls turn into outs.

Tracy isn't alone. While Steve Lombardozzi is 5-for-14 with a double and a triple as a pinch-hitter, everyone else -- mainly Roger Bernadina, Tyler Moore and Tracy -- is a combined 2-for-33 with no extra-base hits.

Overall, those four players are batting .169 with one home run in 177 at-bats. But lately, there have been some more chances for playing time, with Jayson Werth now on the disabled list and Bryce Harper also missing a couple of games.

"This whole game's about playing it every day," Tracy said. "The more you play, the better you get, the more your eyes get trained seeing pitches, the little things that start adding up.

"It's a timing game, where once you get in a rhythm and flow, things start to fall in place. Without that, you're drawing from past experience and trying to get as comfortable as you can from those experiences."

Tracy is the veteran of the bunch and has a leadership role among the reserves. He will dispense advice about pitchers and how to approach at-bats, but he said he doesn't need to "hold their hand."

"Now these guys are thinking like managers," Tracy said. "There's not a whole lot they need to be told."

Worth noting

• Harper was back in the lineup on Sunday playing right field, after missing two games following surgery to remove an ingrown toenail on his left foot.

• Lombardozzi got his first start of the season in the outfield on Sunday. He batted second and played left field.

Lombardozzi played 41 games and started 29 in the outfield last season, all in left. This year, he had started six times at second base and twice at third.

Bernadina and Moore had been getting the starts in the outfield with Werth sidelined for most of the past two weeks. Werth is now on the disabled list with a hamstring injury and won't return until Saturday at the earliest.

Andrew Simon is a reporter for MLB.com. Follow him on Twitter @HitTheCutoff. This story was not subject to the approval of Major League Baseball or its clubs.