Mark Melancon
Those who are just tuning into the Diamondbacks this year because of the World Series might not know Mark Melancon's name, and that's because he hasn't appeared on the mound once in 2023. He signed a two-year, $14 million contract in 2021, with a mutual option in 2024, but didn't do great work for the team in 2022 and sprained his shoulder in spring training this year, which led to a placement on the 60-day IL, which led to him being absent from the mound for the entire season.
Like Evan Longoria and Tommy Pham, Melancon's also getting older, and the Diamondbacks bullpen has proven itself to be an effective force without him, especially during this postseason. Relievers Ryan Thompson, Joe Mantiply, and Kevin Ginkel are all eligible for arbitration this year, and Arizona is much more likely to focus its attentions on maintaining a good relationship with the three of them than concern itself with re-signing a reliever who only managed to give them 56 innings over two years. This one's a no brainer; they've got to let Melancon go.