The Worst MLB Trades of the Decade That GMs Are Still Having Nightmares About
Not every MLB trade is meant to be a blockbuster, but the ones that go wrong can leave a lasting mark. These trades changed careers, frustrated fanbases, and forced front offices into years of damage control. Each one is a reminder that timing and better judgment matter more than bold moves.
Red Sox Trade Mookie Betts to the Dodgers
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The 2020 trade that sent Mookie Betts from Boston to the Dodgers remains one of the most lopsided moves of the decade and a lasting regret for the Red Sox. Boston traded away a 27-year-old former MVP in his prime, along with David Price, for Alex Verdugo, Jeter Downs, and Connor Wong, none of whom matched Betts’ impact. Betts quickly helped Los Angeles win the 2020 World Series, finished second in NL MVP voting, signed a long-term extension, and later added a second Dodgers title in 2024.
Diamondbacks Trade Dansby Swanson to the Braves
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Just six months after drafting Dansby Swanson first overall, Arizona traded him for Ender Inciarte and Aaron Blair to Atlanta for Shelby Miller. Miller’s stint unraveled quickly. Swanson took over as the Braves’ everyday shortstop and delivered above-average production over multiple seasons, including a 2022 All-Star nod and World Series ring.
Mariners Trade Freddy Peralta to the Brewers
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Freddy Peralta was still a teenage prospect when Seattle included him in a trade for Adam Lind in 2015. Lind lasted one year and hit about league average. Peralta matured into one of the most effective starters in the National League and ranked among the leaders in ERA and strikeouts during the 2025 season.
Marlins Trade Luis Castillo to the Reds
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In 2017, Miami dealt Luis Castillo to Cincinnati for Dan Straily after Straily’s surprise career year. Castillo was originally signed by the Giants and traded twice before Cincinnati. The gamble collapsed quickly. Straily’s production fell off, and Castillo turned into Cincinnati’s ace, earning multiple All-Star appearances and leading the staff until the Reds eventually flipped him for another rebuild cycle.
Cardinals Trade Sandy Alcantara and Zac Gallen
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To acquire Marcell Ozuna in 2017, St. Louis sent Sandy Alcantara, Zac Gallen, and two others to Miami. Ozuna hit well but was gone in two seasons. Alcantara won a Cy Young, and Gallen became an ace after Miami flipped him for Jazz Chisholm. That’s a staggering amount of value out the door.
Giants Trade Bryan Reynolds to the Pirates
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San Francisco traded Bryan Reynolds before his MLB debut in exchange for Andrew McCutchen during a short-lived attempt to contend. McCutchen stayed briefly and moved midseason again. Reynolds emerged as a middle-of-the-order fixture, delivered over 20 WAR, and became one of Pittsburgh’s few long-term constants.
Marlins Trade Christian Yelich to the Brewers
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The Marlins traded Christian Yelich to Milwaukee in 2018 for a prospect package headlined by Lewis Brinson. None of the return pieces stuck. Yelich immediately broke out and won the 2018 NL MVP and nearly repeated in 2019. Even after injuries, his impact far outweighed anything Miami recouped in that deal.
Rockies Trade Nolan Arenado and Pay Him to Leave
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Colorado traded Nolan Arenado and $51 million to St. Louis in February 2021 for five players who failed to establish lasting major-league roles. Arenado continued elite defense and strong production, added multiple All-Star appearances and Gold Gloves, and reinforced how little value the Rockies received for a franchise player.
Athletics Trade Away Matt Olson and Matt Chapman
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Oakland traded away Matt Olson and Matt Chapman in 2022 as part of the end of another rebuild cycle. Of the eight players they got in return, only Shea Langeliers has stuck. Meanwhile, both Olson and Chapman remained high-impact regulars and helped their new teams make playoff pushes, with minimal return for Oakland.
Cardinals Trade Adolis García for Cash
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St. Louis traded Adolis García to Texas for cash considerations in December 2019 after limited big-league exposure. García developed into a middle-of-the-order power hitter, earned All-Star selections, and captured 2023 ALCS MVP honors while helping the Rangers win a World Series, thus leaving the Cardinals with nothing in return.