The Mets traded reliever Addison Reed to the Boston Red Sox for three 22-year-old right-handed pitching prospects: Jamie Callahan, Gerson Bautista and Stephen Nogosek.
Boston began Monday a half-game back in the AL East race and was looking to boost its bullpen for a title run.
"We like him a lot. We think he'll come in and be a premium setup guy for us," said Dave Dombrowski, Boston's president of baseball operations. "He makes us deeper in our bullpen. He pushes other guys back to earlier in the game and can close for us when Craig (Kimbrel) needs a day off."
A 28-year-old right-hander, Reed is 1-2 with a 2.57 ERA and 19 saves in 21 chances. He took over as New York's closer this season because of Jeurys Familia's domestic-violence suspension and shoulder surgery. The Red Sox already have a dominant closer in Kimbrel.
Dombrowski indicated that Boston considered quite a few relief options as Monday's non-waiver trade deadline approached. He reached into the left pocket of his suit jacket and pulled out what looked like a piece of notebook paper.
"Twenty right-handed relievers that were on our list at one time or another," he said. "And a lot of lefties, too."
Reed has a $7.75 million salary and can become a free agent after the World Series. New York already has a replacement after acquiring Miami Marlins closer A.J. Ramos on Friday. Ramos is eligible for free agency after the 2018 season.
Callahan, the 87th overall pick in the 2012 amateur draft, is 5-2 with a 3.21 ERA and six saves in six chances at Triple-A Pawtucket.
Bautista is 3-2 with a 5.16 ERA in 32 relief appearances this year at Salem of the Class A Carolina League.
Nogosek is 4-4 with a 3.06 ERA and 19 saves in 23 chances at Salem and Greenville of the Class A South Atlantic League.
"We liked the guys that we traded, but we didn't think we gave up any of our premium guys," Dombrowski said.