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7/30/2014 12:41 A.M. ET

Zimmerman has Grade 3 hamstring strain

MIAMI -- The Nationals have not announced the seriousness of Ryan Zimmerman's right hamstring injury, only indicating that the third baseman is not doing any activities to strengthen the hamstring. However, according to two baseball sources, Zimmerman has a Grade 3 hamstring strain, which means he could be out awhile.

The Nationals did not confirm the diagnosis. A Grade 3 hamstring strain is considered the most severe, involving a tear. Zimmerman, general manager Mike Rizzo and manager Matt Williams were unavailable for comment.

Zimmerman was placed on the 15-day disabled list last Wednesday after straining his hamstring while running to first base against the Rockies the previous day. Zimmerman was scheduled to see the doctor on Monday, but the Nationals have been mum on how he is doing.

"There is still no activity, so we may have something after the game, certainly [Tuesday] when we get here. We'll see what the doctor thinks," Williams said Monday. "He has a pulled hammy and he is not doing anything strength-wise at this point. So it's just kind of a checkup."

Williams had no new information to deliver on Tuesday.

It was learned last week that the Nationals inquired about Rangers third baseman Adrian Beltre, but "were rebuffed." It would come as a surprise if the club tried to acquire an infielder who is a difference-maker like Zimmerman.

Anthony Rendon has taken over as the starting third baseman. He has clearly been the team's MVP this season. But second base is shaky. Zach Walters, Danny Espinosa and Kevin Frandsen haven't proven to be everyday players.

It remains to be seen what the Nationals will do before the non-waiver Trade deadline, which is Thursday at 4 p.m. ET.

Out of lineup, Werth says ankle injury not serious

MIAMI -- Nationals right fielder Jayson Werth was not in Tuesday night's starting lineup against the Marlins because of a sprained right ankle that he injured the previous night.

Although he is listed as day to day, Werth entered the Nats' 3-0 loss in the ninth inning, flying out to right field, and he hopes to back in the lineup by Wednesday. He spent most of pregame getting treatment to get the swelling down in the ankle. Werth believes he needs a day or so to fully recover. He did not have an MRI exam.

"If he [manager Matt Williams] needs me, I'll be available," Werth said before Tuesday night's game. "If it wasn't as bad, I would probably be playing."

In the top of the seventh inning Monday night with the Nationals leading, 6-0, and right-hander Sam Dyson on the mound, Werth hit a leadoff single near the right-field line. Werth tried to stretch it into a double and was thrown out by right fielder Giancarlo Stanton.

"I like to be an aggressive baserunner," Werth said after the game. "I felt when [Stanton] cut the ball off, which was a surprise, I still thought it was going to take a perfect throw. He made a perfect throw. ... I would take that chance tomorrow if I had the opportunity."

After Werth slid awkwardly into second base, he was seen limping back into the dugout. He was replaced by Nate McLouth in right field to open the bottom of the inning. McLouth was in Tuesday's starting lineup.

Detwiler earns bigger role; Blevins a lefty specialist

MIAMI -- Nationals manager Matt Williams announced Tuesday that Ross Detwiler will have a bigger role out of the bullpen, while fellow left-hander Jerry Blevins will be more of a specialist.

Detwiler started the season as just a long reliever, but he has pitched well enough to throw in the late innings. In his last 10 games, the southpaw has a 1.23 ERA, while opponents are hitting .146 against him.

"Det has really come on and pitched well -- right or lefty -- with the exception of last night, when he gave up a couple of hits," Williams said. "You never know what might present itself. It depends on that day and who's available and who's not potentially."

When the Nationals acquired Blevins from the Athletics, he had a reputation of getting lefties and righties out. But so far, right-handed hitters are 23-for-83 (.324) against him, while lefties are 8-for 66 (.121). The emergence of Detwiler has given Blevins a more specialized role.

"If we look at that, we would love to get [Blevins] in some lefty situations," Williams said.

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.