In five Spring Training appearances, Henderson has posted a 1.80 ERA over five innings. He did not allow a hit in three consecutive one-inning stints to start the spring, but yielded three hits and a run to the Marlins on Tuesday in his last outing.
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"I don't know much about the guys here," said Henderson, who spent three seasons with Milwaukee, saving 28 of 32 opportunities in 2013, his last full season in the Major Leagues prior to shoulder problems. "On paper, they have a very good bullpen."
He's throwing in the 90s again, and that gives Henderson optimism for the future.
"I feel good," he said. "I'm able to let it go and throw with some confidence."
Still, few spots remain undetermined in the Mets' bullpen, with righties Jeurys Familia, Addison Reed and Hansel Robles, along with lefties Antonio Bastardo and Jerry Blevins all but assured of spots.
"I'm just here [in Spring Training] working on my body and getting stronger," Henderson said. "We'll see what happens."
The 33-year-old last appeared in a Major League game on May 1, 2014, at Cincinnati. He was placed on the DL the following day with right shoulder inflammation. He remained on the DL and attempted rehab but underwent season-ending surgery on Aug. 19.
He signed a Minor League deal with the Mets on Dec. 3, 2015.
Glenn Sattell is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.