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5/11/2014 1:18 P.M. ET

Walters gets first big league start in left field

OAKLAND -- With ailing first baseman Adam LaRoche (right quad) getting rest, Jayson Werth in the designated-hitter role and Kevin Frandsen at first base on Saturday, Nationals manager Matt Williams trotted out an orthodox lineup against the A's.

Most notably, rookie switch-hitting infielder Zach Walters was starting in left field and batting ninth. Before Saturday, Walter had only played one game as a professional in the outfield, coming in 2012 with Class A Advanced Potomac.

"It's not ideal for us to have to put Zach out there," Williams said. "But he does give us, certainly, more left-handed at-bats tonight against a really tough pitcher [A's righty Sonny Gray]. … Zach's got the ability to change the game with one swing. He's been working out there, he's played out there a little bit, and he's OK, as far as his comfort level out there."

Walters has shown some nice pop in his bat in limited time with the Nationals this season after batting .253/.286/.517 with 29 homers and 77 RBIs for Triple-A Syracuse last season. He's been used exclusively as late-game sub in 2014, batting .167 (3-for-18) with three homers and three RBIs entering play Saturday.

But the biggest concern clearly has to be on the defensive end, given Walters' lack of game experience at the position. Williams still sounded confident in the 24-year-old's athletic ability.

"He's got a really good arm, he's got good speed, he covers ground," WIlliams said. "He hasn't been playing out there every day for the last five years, but he's got the ability to play. He moves around good, he catches balls fine out there."

Quad injury lands LaRoche on 15-day DL

OAKLAND -- Shortly after Saturday night's deflating 4-3 loss in 10 innings against the A's, the Nationals announced more bad news.

Manager Matt Williams said first baseman Adam LaRoche, the team's top all-around hitter so far this season, will be placed on the 15-day disabled list to rest his strained right quadriceps.

The move became official Sunday, and the team recalled first baseman/outfielder Tyler Moore from Triple-A Syracuse. Moore returns after spending 18 games with the Nationals earlier this season.

LaRoche was originally slated to play first base on Saturday but was removed from Friday's contest as designated hitter after feeling it flare up.

An MRI on Saturday confirmed the bad news for the Nationals, with Williams terming it a high quad/hip flexor strain. 

"Don't want to do it," Williams said of placing LaRoche on the DL, "but for the long-term health of Adam and our team, it's probably important to do that right now and make sure we can calm it down as much as possible. Nobody is going to feel sorry for us; we've got to play."

LaRoche is batting .319/.421/.504 with five homers and 21 RBIs in 32 contests. Now he heads to the DL to join other sluggers Bryce Harper and Ryan Zimmerman, who are both dealing with thumb issues that require lengthy recoveries.

"It [stinks] not being able to go out there every night and battle with the guys," LaRoche said. "The one thing I do feel good about is that I gave it every opportunity to try and go out and play through it, and see if this thing would go away. The last couple days have proven that it's just not going happen."

LaRoche said he will probably stay with the team as it wraps up the road trip in Arizona, but that he's looking forward to resting it for five or six days with no activity.

"We gave it probably 10 days of hurting pretty good," LaRoche said. "Any time I'd go to make a move, it wouldn't make it any better. Going to take two weeks and try to get right, rather than risk [missing] six or eight weeks."

Hand feeling better, McLouth back in starting lineup

OAKLAND -- Nate McLouth was back in the Washington starting lineup on Saturday for the first time since cutting his hand while colliding with a wall on Monday making a diving catch. The veteran outfielder appeared as a ninth-inning defensive replacement on Wednesday but had been otherwise giving his hand time to recover.

"There was no way it would have healed if I kept swinging," McClouth said. "But I hit [Friday], and it's good to go."

McLouth has a small bandage near the knuckle at the base of his right index finger. While grabbing the ball on defense hasn't been much of a problem, he's noticed the injury when swinging the bat.

"Right where the hand and the bat went, right over that, it's a flesh wound," McLouth said. "It's gotten enough skin to where I can put some stuff -- I don't know what it is, it's kind of like superglue -- on there. So there's a little shell over it."

The Nationals signed McLouth to a two-year deal worth at least $10.75 million, with a club option for 2016, but he hasn't produced much offense for his new club. In his first 27 contests for Washington, McLouth batted .085 (4-for-47) with a double, a home run and an RBI.

Manager Matt Williams said he doesn't know what McLouth has to do to get out of his season-long funk.

"If I had that answer, man, I wouldn't be doing what I'm doing," Williams said. "Nate, he's just got to play. He's got a history of being able to hit, so he'll come out of it. He'll be fine, and more at-bats will certainly help."

Worth noting

• Friday night, the team matched a season high with three errors, and there were other notable misplays as well. Entering play Saturday, Washington had committed the third-most errors in Major League Baseball (32), trailing only the Indians (35) and the Dodgers (34).

"Everybody's going to make errors, but you certainly don't want to make multiple errors in a game," Williams said after his team committed three for the third time this season. "Today was a case where we did that. You've got to help yourself. Any team that you're playing and you give them extra outs, you're asking for trouble."

• Williams offered an update on Harper (left thumb surgery), saying Harper either had his stitches removed recently or would have them removed in the near future. Harper is expected to be out until July.

•  Williams also said Zimmerman (broken right thumb) hasn't resumed baseball activities yet. Zimmerman will receive another X-ray on Sunday, Williams said. Saturday marked the four-week mark since Zimmerman injured his hand sliding into third base, and the initial timetable for his return called for four to six weeks.

Alex Espinoza is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.