The trade deadline may be the time of year when contending teams add various supplemental pieces for the stretch run, but the MLB offseason is when contenders are actually built.
Over the years, some of the greatest additions to championship rosters have been made during the winter months when baseball itself is dormant. Let's look at the 25 biggest offseason moves that have helped pave the way for teams to take home the World Series trophy.
Los Angeles Dodgers: Blake Snell & Roki Sasaki (2025)
Blake Snell parlayed his two Cy Young seasons into a mega-deal with the Dodgers, and Roki Sasaki was one of the top international signings in 2025. Snell may have taken the loss in both of his World Series starts, but his relief appearance in Game 7 kept LA's deficit to just one run in the eighth inning. Sasaki was the Dodgers' secret weapon, posting a meager 0.71 ERA with three saves during the playoffs en route to their second straight World Series title.
Los Angeles Dodgers: Shohei Ohtani & Yoshinobu Yamamoto (2024)
The Dodgers World Series hopes got an unfathomable boost after adding the best player on the planet. Two-way superstar Shohei Ohtani signed a record-breaking 10-year, $700 million deal during the 2024 offseason. Not to be outdone, Los Angeles also inked Japanese sensation Yoshinobu Yamamoto to a 12-year, $325 million contract. These two free agent signings, who combined contracts are worth over $1 billion, set the stage for LA's second World Series win in five years.
Los Angeles Dodgers: Mookie Betts (2020)
MLB has seen their fair share of lopsided trades, but few throughout the storied history of the game will match the Dodgers' deal for Mookie Betts. LA shipped Alex Verdugo, Connor Wong, and Jeter Downs to Boston for the former MVP. Los Angeles then signed Betts to a 12-year, $365 million contract extension and reaped the rewards later that fall after winning their first World Series championship since 1988.
Washington Nationals: Patrick Corbin (2019)
Patrick Corbin had an All-Star season with the Diamondbacks in 2018 and turned that into a six-year, $140 million deal with the Nationals. His relief performance during Game 7 of the World Series — a scoreless sixth, seventh, and eighth inning — earned him the win and gave the Nats their first ever championship. Corbin's career fell off a cliff after his first year in DC, but that's the one that matters most.
Boston Red Sox: J.D. Martinez (2018)
J.D. Martinez signed a five-year, $110 million contract with the Red Sox and became an All-Star during his first year in Boston. He mashed 43 homers and racked up 130 RBI. The slugger had three massive home runs during the Red Sox's march through the playoffs, including one during Boston's series-deciding Game 5 win over the Dodgers during the World Series that brought yet another championship back to Beantown.
Houston Astros: Josh Reddick (2017)
The Astros' 2017 championship team was made up of mostly homegrown talent, but the addition of Josh Reddick — who signed a four-year, $52 million deal — gave Houston a reliable veteran presence in the outfield. Reddick's bat lagged behind his glove during the postseason, but a wall-crashing robbery of Yankees infielder Chase Headley during the ALCS and his overall defensive performance, helped propel the Astros to their first ever World Series championship.
Chicago Cubs: Ben Zobrist (2016)
Ben Zobrist reunited with his former manager Joe Maddon in Chicago after signing a four-year, $56 million deal with the Cubs. Zobrist will forever be remembered as the catalyst who broke the 108-year curse after driving in the go-ahead run for Chicago during the 10th inning of Game 7 against Cleveland. He was named World Series MVP and was part of a World Championship team for the second year in a row.
San Francisco Giants: Tim Hudson (2014)
Tim Hudson's 2013 season ended prematurely due to injury, and during the offseason he landed a two-year contract with the Giants. At 39 years old, he made 31 starts in 2014 and racked up almost 200 innings. Hudson was named an All-Star for the fourth time that year, and became the oldest pitcher to start Game 7 of the World Series. While most Giants fans probably remember Madison Bumgarner's five-inning save, Hudson's efforts certainly cannot go unnoticed.
St. Louis Cardinals: Lance Berkman (2011)
The Yankees declined Lance Berkman's option for 2011, and he joined the Cardinals on a two-year deal. He was named NL Comeback Player of the Year, finished seventh in the NL MVP race, and was key to St. Louis' championship run. He hit a tone-setting home run during the first inning of Game 6, and his RBI single during the 10th inning knotted the game at 9-9. That set the stage for David Freese's historic home run in the bottom of the 11th.
San Francisco Giants: Aubrey Huff (2010)
Aubrey Huff signed a one-year, $3 million deal with the Giants after a disappointing season split between Baltimore and Detroit the year before. He had a bounce back season in the Bay Area, hitting .290 with 26 homers and 86 RBI. His offensive outburst continued into the postseason, which included a huge two-run blast during Game 4 of the World Series. He went 5-for-17 during the Fall Classic, and helped bring the Commissioner's Trophy back to San Fran for the first time in 56 years.
New York Yankees: CC Sabathia & Mark Teixeira (2009)
Hall of Famer CC Sabathia and All-Star slugger Mark Teixeira signed for a collective $321 million with the Yankees during the 2008-09 offseason. Sabathia finished fourth the AL Cy Young vote that year, and Teixeira came in second in the AL MVP race. Sabathia was named ALCS MVP, and though Teixeira's production dipped a bit during postseason, the duo helped lead New York to their 27th World Championship with a sweep over the Philadelphia Phillies.
Boston Red Sox: Daisuke Matsuzaka (2007)
After a successful career overseas, Daisuke Matsuzaka landed with the Red Sox in 2007 after being posted by the Seibu Lions during the offseason. He was on the mound for Game 3 of the World Series that year, and went 5â…“ innings, allowing just two runs on three hits while striking out five. But it was a Matsuzaka's two-run single that stole the show (you know, when pitchers used to actually hit) and helped propel Boston to a four-game series sweep over the Rockies.
Chicago White Sox: Jermaine Dye (2005)
Jermaine Dye was non-tendered by the Oakland Athletics after the 2004 season, but landed a two-year, $10 million deal with the White Sox that winter. He crushed 31 home runs that season while slugging .512 and posting 86 RBI. But his play during the World Series that year took on a life of its own. Dye went 7-for-16 (.438) and his RBI-single during the eighth inning of Game 4 sealed the deal and capped off the White Sox's sweep over the Astros.
Boston Red Sox: Curt Schilling (2004)
Curt Schilling made a name for himself during the Diamondbacks' World Series run 2001, but was part of a five-player trade with the Red Sox after the 2003 season. He won 21 games for Boston in 2004 and finished second in the Cy Young voting behind Johan Santana. Most baseball fans will probably remember Schilling's infamous 'bloody sock' during Game 6 of the ALCS against the Yankees. He helped lead the Red Sox rotation, and reverse the Curse of the Bambino after defeating the Cardinals in the World Series. It was Boston's first World Series title in 86 years.
Miami Marlins: Ivan Rodriguez & Juan Pierre (2003)
Ivan Rodriguez signed a one-year deal with the Marlins prior to 2003, while Juan Pierre arrived via a trade from the Rockies. Rodriguez gave the Marlins a veteran presence behind the dish, and Pierre led the National League in steals (65). Both received down-ballot votes for MVP that year. Pierre recorded a stolen base during each round of the postseason in 2003 and Rodriguez was named NLCS MVP. The two helped lead the Marlins to a World Series victory over the vaunted Yankees in what was one of the most David versus Goliath October matchups ever.
Arizona Diamondbacks: Reggie Sanders & Mark Grace (2001)
Curt Schilling and Randy Johnson led the way for the Diamondbacks pitching staff in 2001, but the veteran additions of Reggie Sanders and Mark Grace cannot go unnoticed. Both were standout performers during their time in the NL Central. Sanders notched a key homer during the NLDS, and Grace's leadoff base hit during the bottom of the ninth inning in Game 7 of the World Series set the stage for the D-backs' comeback win against Mariano Rivera and the Yankees.
New York Yankees: Roger Clemens (1999)
The Blue Jays traded Roger Clemens to their hated AL East rival, the Yankees, during spring training in 1999. His regular season performance (14-10 4.60 ERA) wasn't what most Yankees fans were expecting to see from the reigning two-time Cy Young award-winner. But Clemens ratcheted things up during the playoffs, throwing seven shutout innings during New York's ALDS win over the Rangers. He went into the eighth inning during his start in the Yankees' Game 4 series-clincher over the Braves, and helped New York take home back-to-back World Series trophies.
Miami Marlins: Moisés Alou (1997)
A long time member of the now-defunct Montreal Expos, Moisés Alou signed with the Marlins prior to the 1997 season. During his lone season in South Beach, Alou hit .292/.373/.493 with 23 homers and 115 RBI. He was named to the NL All-Star squad and finished 10th the MVP voting that year. Alou starred for the Marlins during the Fall Classic, going 9-for-28 with three home runs and nine RBI to help lead the franchise to their first ever World Series championship.
Blue Jays: Paul Molitor (1993)
Paul Molitor was well on his way to a Hall of Fame career before signing a three-year deal with the Blue Jays following the 1992 season. He mashed 22 home runs and recorded 111 RBI during his first year north of border, and his performance during the Fall Classic earned him World Series MVP honors. Molitor was 12-for-24 during the World Series with two doubles, two triples, and two homers. The Jays knocked off the Phillies in six games to take home their second straight World Series title.
Minnesota Twins: Jack Morris (1991)
Legendary Tigers' pitcher Jack Morris spent 14 years in the Motor City, yet it wasn't overly shocking to see the Hall of Famer inked a one-year deal with his hometown Twins during the 1990-91 offseason. We was All-Star in Minnesota that year and finished in the fourth in the Cy Young voting after going 18-12 with a 3.43 ERA. But it was Morris' iconic performance during Game 7 of the World Series — 10 innings of shutout baseball — that gave him perhaps the greatest honor of his career. He won World Series MVP and brought a championship back to his hometown in Minneapolis.
Los Angeles Dodgers: Kirk Gibson (1988)
"In a year that has been so improbable, the impossible has happened." There might not be a more iconic moment in the history of Major League Baseball than than Kirk Gibson's walk-off home run off Athletics closer Dennis Eckersley during Game 1 of the 1988 World Series. Vin Scully's, "High fly ball into right field. She is gone," will live in the annals of baseball lore forever. That moment alone makes Gibson's signing with the Dodgers one of the biggest offseason additions in the history of the sport.
New York Yankees: Goose Gossage (1978)
Rich "Goose" Gossage spent the first several years of his career with the White Sox and Pittsburgh, but signed a six-year deal with the Yankees after the 1977. He led the league in saves during the 1978 season, was named to his four consecutive All-Star Game, and finished fifth in the AL Cy Young race. The Hall of Famer pitched in two games during New York's ALCS win over the Royals, and only gave up one hit during the Yankees 4-2 World Series win over the Dodgers. It was the Yankees' second straight World Title, but they wouldn't win another until another Hall of Famer, Mariano Rivera, was handling closing duties in the Bronx.
New York Yankees: Reggie Jackson (1977)
There would be no Mr. October if the Yankees hadn't signed Reggie Jackson ahead of the 1977 season. The Hall of Famer's performance during the World Series that year is legendary. He went 10-for-20 with five home runs and eight RBI. Chase Utley (2009) and George Springer (2017) have both matched Jackson's five home run feat, but the Mr. October moniker isn't going anywhere. Jackson helped the Yankees win their first of two World Championships during his tenure in the Bronx.
Baltimore Orioles: Frank Robinson (1966)
The Reds traded Frank Robinson to the Orioles in December of 1965 in exchange for Milt Pappas, Jack Baldschun, and Dick Simpson. Those three players did nothing after coming to Cincinnati, but during his first season in Baltimore, Robinson won the Triple Crown, hitting .316 with 49 homers and 122 RBI. He earned the AL MVP award that year, and led the Orioles to their first-ever World Series title. Robinson won another World Series title with the O's in 1970 over his former team, the Reds.
St. Louis Cardinals: Rogers Hornsby (1926)
We saved the best for last, and took a few liberties to squeeze this one in, but the story itself is worth it. Midway through the 1925 season, Rogers Hornsby replaced Branch Rickey as manager — though he was already a player in the Cardinals organization. The maintained the role during the offseason and into 1926. To call it an 'offseason move' is certainly a stretch, we admit, but stick with us.
After winning MVP in 1925, Hornsby put up some of the worst numbers of his career in 1926 (.317/.388/.463), but the Cardinals still won the NL pennant and faced off against the Yankees in the World Series. Hornsby, however, received the heartbreaking news that his mother passed away on the eve of the Game 1, yet a telegram from his uncle citing his mother's desire for him to play kept Hornsby from rushing back to Texas.
The World Series went to a deciding Game 7, and Hornsby made the game-winning play, applying the tag to Babe Ruth who was attempting to steal second base during the bottom of the ninth. The throw from catcher Bob O'Farrell to a covering Hornsby was in time and preserved St. Louis' 3-2 victory. It was Hornsby's only World Series title during his Hall of Fame career.
Apologies to Marquis Grissom (Braves -1995), Scott Brosius (Yankees -1998) , Charlie Morton (Braves - 2021), Nathan Eovaldi (2023) who just missed the cut.
Add us as a preferred source on Google