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04/23/2013 7:29 PM ET

Stammen impressing with early performance

WASHINGTON -- Nationals manager Davey Johnson didn't want to use Craig Stammen on Monday night. The skipper wanted to give Stammen a two-day break, but that didn't happen.

Stammen threw two scoreless innings in Monday's 3-2 loss to the Cardinals, and that left Johnson shaking his head again about how much the right-hander's been helping.

"He can give you a bunch of innings," Johnson said. "He's been a big part of the winning effort here."

Stammen entered Tuesday night's game with a 2-1 record and 3.38 ERA. He had already pitched in seven of the team's 19 games and was very strong in his last three appearances.

Stammen struck out seven in 5 2/3 innings over those three games. In Monday's game, Stammen threw a pair of scoreless innings and got out of a major jam in the sixth inning after coming in for Dan Haren, getting a 3-2-3 double play with the bases loaded and then, following an intentional walk, striking out Cards pitcher Shelby Miller to end the inning.

Haren frustrated, but Nats have confidence

WASHINGTON -- It was easy to see the frustration on right-hander Dan Haren's face after Monday's game. Haren went five-plus innings and gave up three runs in the loss to the Cardinals.

Haren has struggled throughout his first four starts. He's yet to record an out in the sixth inning this season and said after Monday's game that he wants to be more consistent and effective.

Manager Davey Johnson said after the game and before Tuesday's contest that he liked what Haren showed in that start. The skipper said he saw improvement.

In addition, Nationals general manager Mike Rizzo said during batting practice before Tuesday's game that he's completely confident in Haren. He said the veteran's just working his way through the kind of early-season slump that's not much fun.

"I think that he's a consummate professional," Rizzo said. "He's been through these slumps before, and I think he is getting better each and every start. He knows how to pitch in this league. His track record speaks for itself."

Both Johnson and Rizzo are confident that Haren will be able to right himself and be the kind of pitcher the Nationals expected when they signed him during the winter.

Rendon gives ball from first hit to mother

WASHINGTON -- Anthony Rendon was in the lineup again Tuesday, the third straight game he had started since coming up to the Majors on Sunday.

Rendon entered having batted .125 over the first two games, and  he will likely get plenty of playing time while third baseman Ryan Zimmerman is on the disabled list (left hamstring strain).

The rookie said he got plenty of text messages after getting his first big league hit in Monday's 3-2 loss to the Cardinals.

"I got a good amount," he said. "I guess it's a good thing. I've got a lot of people behind me."

Rendon got the ball from that first hit (an RBI double) and did what any good son does. He gave it to his mother.

"You've got to," Rendon said with a smile.

Worth noting

• Johnson said he believed that closer Rafael Soriano was available for Tuesday's game. Soriano missed Monday as his wife had a baby boy.

• Johnson also joked about how the local broadcast showed the former second baseman doing some push-ups during Monday's game. "I was trying to get some blood flowing. I didn't know it was going to be televised," he said with a laugh.

• The Nationals (10-9) entered Tuesday as one of just three teams in the Major Leagues that had a winning record with a negative run differential; they were minus 15.

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