As the Mets enter the homestretch of their most promising season in years, they will be missing one of their top home run hitters for longer than they expected.

Lucas Duda has yet to begin swinging a bat, Terry Collins said Monday. His slow progress from a herniated disc in his back means he likely won't be activated from the DL when he's eligible Saturday. "He's doing stuff, but he hasn't swung a bat," Collins said.

Duda remains at the team's complex in Port St. Lucie, Florida, where he fielded grounders Monday. The closest he's come to hitting has been tracking pitches off a pitching machine in an effort to keep his timing intact.

Photos18 Mets who have been on the DL in 2015

Daniel Murphy and Michael Cuddyer have shared time at first, but the Mets have been without a major power threat. Duda has 21 homers.

Fresh arm in Reed

Addison Reed hadn't officially been a Met for long when a fan asked him on Twitter to evaluate his dislike for the Nationals on a scale of one to 10. The response: 25. "I didn't think it would be anything," said Reed, whose response after his trade from the Diamondbacks reflected his excitement about joining a pennant race.

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The Mets hope Reed stabilizes a bullpen that has lacked a reliable option ahead of Tyler Clippard and Jeurys Familia. "We're hoping that he's that guy who can get us to the eighth inning," Collins said.

Since returning in late July from a demotion to the minors, Reed has a 1.65 ERA in 13 games. The turnaround came about with mechanical adjustments that led to improved command. He also regained the feel for his slider.

"I was throwing the ball and I had no idea where it is going," said Reed, who gives the Mets another reliever with big-league closing experience.

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Extra bases

Collins said he wanted to see how Steven Matz fared in Monday night's rehab start (one hit in 5 1/3 scoreless innings for Binghamton) before divulging where he'll slot into the rotation . . . Rosters expand Tuesday, and Collins said Matz and reliever Erik Goeddel will be active for Tuesday night's game. Goeddel had a 1.96 ERA in 22 games before an elbow strain sent him to the DL in mid-June . . . To clear a spot on the 40-man roster for Eric Young Jr., the Mets outrighted Danny Muno to Las Vegas.