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6/11/2014 10:08 P.M. ET

Zimmerman impressing in outfield play

SAN FRANCISCO -- Nationals outfielder Ryan Zimmerman is doing better in the outfield than any baseball expert thought. He has been catching balls in the gap and has made some nice running plays while running in on the ball. Manager Matt Williams has been impressed by what he has seen from Zimmerman so far.

"He has gone to each gap. He has gone down the line. He is coming in on line drives right at him. He has fielded everything cleanly with ease. That part of it has been a pleasant surprise," Williams said. "He seems to be enjoying it."

Although Zimmerman is playing well in left field, it does not mean he will stay there for the rest of the season. Once Bryce Harper comes back from his thumb injury in July, Zimmerman will return to third base, while Anthony Rendon returns to second base. Second baseman Danny Espinosa will be back on the bench.

"We have a pretty good outfielder [in Harper]. Hopefully, he comes back real soon," Williams said. "The perfect world is that Zimmerman will go back to third, where he has played for a long time. He won a Gold Glove. When Harp is ready, he will play left. By that time Wilson [Ramos] returns, we'll be at full strength. That is the plan."

Ramos goes on disabled list with tight hamstring

SAN FRANCISCO -- The Nationals placed catcher Wilson Ramos on the 15-day disabled list Wednesday because of right hamstring tightness. The team recalled catcher Sandy Leon to be the No. 2 catcher.

Ramos hurt the hamstring Tuesday after batting in the ninth inning against Giants right-hander Juan Gutierrez. Ramos doubled to left-center field and felt pain as he was sliding into second base. Ramos left the game and was replaced by outfielder Nate McLouth. Ramos walked back into the dugout on his own power.

Ramos had an MRI on the hamstring Wednesday and it revealed a Grade 1 strain, according to manager Matt Williams.

"It's going to be a few days at least," Williams said. "If it were a couple of days, it may be fine. A doctor looked at it, studied it and thought a week to 10 days anyway. So we made sure it's taken care of and he is back in 15 days. The thing we don't want is he gets out there and plays and it gets worse and you are looking at 30 days."

It marked the second time Ramos has been placed on the disabled list this season. The first time came a day after Opening Day when he broke his left hamate bone.

On Wednesday, Ramos was upbeat and "normal," but he understood why he was placed on the DL. He realizes the Nationals need to have a healthy catcher in case something happens to Jose Lobaton, who was in Thursday's starting lineup.

"They put me on the DL because they need to have somebody 100 percent in case Loby gets hurt or something like that. They need to get somebody ready," Ramos said. "I want to work. I want to keep working. Let's see how I feel the next couple of days."

Ramos is in great shape, but Lobaton suggested to Ramos that he needs to start a new program in order to keep his legs healthy. Ramos agrees with his teammate. Ramos had hamstring issues last year and missed half the season. The hamstring injuries have been caused by running the bases.

"I need to do something different," Ramos said. "I need to work more on my hammy. I need to work on my hammy because I don't have any problem with any part of my body, just my hammy. I need to work 100 percent with my hammy."

As for Leon, this is his second stint with the Nationals this season. He is having a productive year with Triple-A Syracuse, hitting .294 with six RBIs.

Gio slated for second rehab outing, could return soon

SAN FRANCISCO -- Nationals left-hander Gio Gonzalez, on the disabled list with left shoulder inflammation, will pitch in his second rehab game for Class A Advanced Potomac on Thursday. Manager Matt Williams said that if things go well, Gonzalez will be back with the Major League team next week.

In his last start for Potomac, Gonzalez was hit hard, allowing eight runs in 3 2/3 innings, and the Nationals declined to bring him back to the big leagues.

With Gonzalez expected to come back, the Nationals most likely will send Blake Treinen back to Triple-A Syracuse. Treinen has been outstanding during his brief time with the Nationals, allowing five earned runs in 25 1/3 innings. He is scheduled to start against the Giants on Thursday afternoon.

Williams admitted it would tough to send Treinen down.

"It's never easy, but he is still in the learning process as far as starting pitching goes," Williams said. "... But it's never easy to send somebody out, especially when [he has] contributed to your team's winning and has done the job that he has done for us."

Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the Time. He also can be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.