"It's pretty typical plantar fasciitis," manager Matt Williams said before Thursday night's game against the Brewers. "It's not getting any better. Over the last three or four games, it's just really bothering him."
Williams said the key for Zimmerman now is to stay off the injured foot.
"Right now, it's total rest," Williams said. "So he'll get off of it for a few days and not push it too hard. Let it calm down. Hopefully in 15 [days], he's ready to go. Generally, when it's gone, it's gone."
den Dekker, 27, joins the Nationals for the third time this season. A member of the Opening Day roster, den Dekker appeared in four games for the Major League team, going 0-for-2 in two at-bats off the bench. He was also added last week as the 26th man for the nightcap in a Nationals' doubleheader split with Toronto, but he did not appear in the game.
In 47 games for Syracuse this season, den Dekker has hit .234 (41-for-175) with seven doubles, two home runs, 20 RBIs, 16 walks and eight stolen bases.
While den Dekker provides outfield depth for the Nationals, there are questions surrounding the infield, especially at first base. The Nationals could turn to any one of Tyler Moore, Clint Robinson or Danny Espinosa.
"We'll have to mix and match," Williams said. "The good thing is we have a couple of guys that know how to play. They understand how to play. We can have some versatility within our infield because we have multiple guys that can play multiple positions."
As for Espinosa, Williams said it's time for the utility infielder to get in some reps at first base.
"Danny will take some grounders over there just in case we need him." Williams said. "He'll get some work for sure."
Brandon Curry is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.