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7/31/2014 7:06 P.M. ET

Zimmerman shut down for at least two weeks

No official diagnosis on severity of Nats third baseman's hamstring injury

WASHINGTON -- MLB.com reported early Wednesday morning that Ryan Zimmerman's right hamstring injury is a Grade 3 strain, which likely involves a tear that could leave him on the disabled list for the rest of the regular season.

However, the Nationals did not offer an official diagnosis on the severity of Zimmerman's injury. On Thursday, manager Matt Williams said there was no new information beside the fact that Zimmerman would "do nothing" for two weeks before the team re-evaluates the condition of his hamstring.

If the Nationals see improvement during that reevaluation in two weeks, Zimmerman could begin strengthening exercises, Williams said. But until then, the future of Zimmerman's 2014 season remains in limbo.

"You don't know until he starts strengthening it, until he starts doing stuff with it and [you can see] how it reacts," Williams said. "Guys heal at different speeds, so it depends on what he can do after the two-week process, and then we evaluate again after that. But there's not going to anything new for a couple weeks because he's not doing anything. There's not tests that we can put him through that would say, 'Well, you've progressed X amount,' or anything like that because he's just shut down."

The Nationals provided a glimpse into the potential severity of Zimmerman's injury when they traded for Indians infielder Asdrubal Cabrera before Thursday's non-waiver Trade Deadline. Cabrera will take over the starting job at second base, and general manager Mike Rizzo said Zimmerman's absence was the deciding factor in the deal.

"With a healthy Zim and a healthy eight players that we had, we certainly wouldn't have found the need to go out and acquire a player as skillful as Cabrera," Rizzo said. "When Zim went down, to protect ourselves, we felt we should go out and get ourselves a good veteran, a person to fit into the lineup."

Zimmerman, who missed 44 games earlier this season with a fractured thumb fracture, was on the field for batting practice Thursday afternoon with his glove, wearing sneakers and baseball pants. He walked gingerly around the diamond and engaged in conversation with a number of his teammates, but he didn't participate in any physical activity.

Williams delivers trade news for first time as manager

WASHINGTON -- When manager Matt Williams called Zach Walters into his office early Thursday, the young infielder thought he was in trouble. It was only after Williams delivered the news that the reality of the situation sunk in: Walters had been traded to the Indians for infielder Asdrubal Cabrera and he was no longer a member of the Nationals.

"It's shock because you don't what to do. You don't know who to call or who to talk to or when you need to leave or what you need to do or where they're at because you never think about that," Williams said. "It's the reality of the business of baseball sometimes. But you care for people."

The process was nothing new to Williams, though. After all, the five-time All-Star was traded twice during his Major-League career -- from the Giants to the Indians in 1996 and then from Cleveland to the D-backs in 1997.

Even so, having to deliver the news as opposed to receive it certainly provided a different perspective for the first-year skipper.

"I've been on the other side of it, so I understand it," Williams said. "But again, we as coaches get to know these guys. This is family. So it's never easy."

Worth noting

• The Nationals recalled right-hander Blake Treinen from Triple-A Syracuse on Thursday to fill the extra roster spot created after Walters was traded to the Indians.

• Washington first baseman Adam LaRoche was a late scratch from the lineup Thursday night. Kevin Frandsen started in his place to give LaRoche a breather.

Daniel Popper is an associate reporter for MLB.com. He also can be found on Twitter @danielrpopper. This story was not subject to the approval of Major League Baseball or its clubs.