Ryan Zimmerman apparently injured his arm on this slide. (Richard Carson/Associated Press)

Ryan Zimmerman was not in the lineup for Friday’s 4-2 loss to the New York Mets, and that made perfect sense. Zimmerman looked tired the last few days in Houston, particularly as he got up from his headfirst slide into home plate with the go-ahead run late Thursday night. He joked about it after, moving around the clubhouse as normal.

But apparently, something is not normal with Zimmerman’s arm. After Friday’s loss, Dusty Baker revealed that Zimmerman was out of the lineup due to injury — the specifics of which he did not disclose — and added that the first baseman will probably be out of the lineup again Saturday.

“I think he hurt his arm or shoulder — really couldn’t swing — on his headfirst slide yesterday into the plate,” Baker said. “I don’t anticipate he’ll be much better tomorrow, but hopefully on Sunday.”

Baker did not specify which arm Zimmerman injured. The first baseman has a well-documented history of right shoulder trouble, trouble that grew so bad he had to convert from third base to first base to avoid throwing as much as possible. He also has a lengthy injury history in recent years, and had tiptoed out of the way of injury this season, which turned into one of the best of his career.

But Zimmerman has appeared tired, his swing a tick slow. He is hitting just .219 in August — the lowest average of any month of this season, in which his average has declined steadily, month by month. The Nationals have Adam Lind to fill in regularly at first base in his absence, but any prolonged loss of Zimmerman would deal a blow to the already decimated Nationals batting order, just at the time of year they targeted to start bringing it back together.

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