2) Chris Martin
Arguably the best option that the Mets can realistically trade for is Chris Martin, another reliever who comes at a better cost and coming off a superb year.
In 55 appearances for the Red Sox last season, Martin posted a 1.05 ERA in 51.1 innings of work. He was so good, in fact, that he finished 12th in the AL Cy Young voting despite not even being their closer. He displayed absurd command, allowing just two home runs and eight walks (three of which were intentional) all season.
While it's almost impossible for Martin to be that good again next season, he is a guy who has been consistently solid throughout his career. He has a 3.36 ERA in 324 MLB appearances across parts of eight seasons, two-and-a-half of which were spent in the NL East with the Braves.
Emilio Pagan signed a two-year deal with the Reds this offseason at $16 million. Cincinnati gave a lesser reliever more in terms of AAV, and an additional year. There's nothing wrong with the Pagan deal, but it shows how valuable Martin is at his pricepoint.
The Mets desperately need at least one, preferably two late-game relievers to form a bridge to Edwin Diaz alongside Brooks Raley. Getting Martin who is set to make just $7.5 million next season in a salary dump that wouldn't involve giving up much in return would be a huge get for the Mets.