10 big offseason additions who have been crucial for contenders

When teams make major offseason additions, they do so with the hope that they’ll pay immediate dividends in Year 1, helping their new clubs contend for a postseason berth and, potentially, a World Series title.

Each of the players below has done just that, excelling in a new environment and aiding his club’s playoff push.

With the regular season winding down, here’s a ranking of the top 10 offseason additions contributing for postseason contenders, based on personal performance and the overall impact they’ve had with their new clubs. (All stats below are through Sunday’s games.)

1. Dansby Swanson, SS, Cubs
How acquired: signed in free agency

One of four star shortstops who hit free agency last offseason alongside Trea Turner, Carlos Correa and Xander Bogaerts, Swanson signed the lowest deal of the four in terms of guaranteed money ($177 million). But no offseason addition has made as big of an impact as the 29-year-old in 2023. Combining his stellar defense (MLB-leading +19 OAA) and solid offensive production (20 HR, .750 OPS), Swanson has recorded 4.7 WAR, per FanGraphs.

Meanwhile, Nico Hoerner has posted a 4.5 fWAR season at second base, his new home after the Swanson signing. Hoerner had 4.0 fWAR as the Cubs’ primary shortstop a year ago, but the team’s second basemen combined for 0.8 fWAR. The Cubs’ excellent middle-infield duo has been integral in their rise from also-ran in 2021 and 2022 to a Wild Card contender in 2023.

2. Sean Murphy, C, Braves
How acquired: trade with A’s, Brewers

Already one of baseball’s best defensive catchers, Murphy has taken a step forward on offense following an offseason trade from Oakland to Atlanta. The 28-year-old has produced a career-high 20 homers with an .872 OPS over 101 games for the Braves, who clinched their sixth straight NL East title and are on pace to post baseball’s best record. Murphy has also continued to flash excellent defensive tools behind the plate, posting the fifth-highest fielding run value (13 runs prevented) in MLB.

There’s certainly a case to be made for Murphy at No. 1 on this list. But considering the Braves likely would have still won this division if they had William Contreras -- the player Murphy replaced in Atlanta’s catching tandem with Travis d'Arnaud -- we’ll put him in the second spot behind Swanson.

3. Cody Bellinger, OF, Cubs
How acquired: signed in free agency

The Cubs really nailed free agency last offseason, didn’t they? Bellinger wasn’t expected to be part of last year’s free-agent class, but he was non-tendered by the Dodgers after posting a .193/.256/.355 slash across 2021-22. Chicago signed Bellinger to a one-year deal worth $17.5 million in guaranteed money with the hope that he would recapture the form he showed while winning the NL Rookie of the Year Award in 2017 and the MVP two years later.

The 28-year-old has enjoyed a resurgence on the North Side of Chicago, producing a 25-homer, 20-steal campaign with a .311 average, an .890 OPS and 4.0 fWAR in 119 games. With his ability to test free agency again after 2023, Bellinger was a candidate to be dealt leading up to this year’s Trade Deadline. However, the Cubs have surged back into the NL Wild Card race behind Bellinger’s .322/.356/.573 performance in the second half.

4. Luis Arraez, 2B, Marlins
How acquired: trade with Twins

In need of an offensive boost, Miami dipped into its pitching depth last offseason, dealing Pablo López and two prospects to the Twins for Arraez, the reigning AL batting champ. Arraez has been an incredible addition for the Marlins, posting an MLB-leading .353 batting average with 199 hits in 143 games. His production has helped the club remain in the hunt for what would be just the fourth postseason berth in franchise history (1997, 2003, 2020). Arraez can also make history on an individual level -- if he holds on to win the NL batting title, he’d become the first AL/NL player to capture a batting crown in one league and then win one in the other league the following year.

5. Pablo López, SP, Twins
How acquired: trade with Marlins

In the rare trade where both sides came away satisfied, the Twins acquired López and two prospects from the Marlins for Arraez last January. Aside from a rocky stretch in the middle of the season, López has been outstanding for Minnesota, notching a 3.58 ERA with a career-high 221 K’s over 183 2/3 innings. The 27-year-old has been especially dominant over his past 11 starts, pitching to a 2.42 ERA with 76 K’s over 67 innings to help the Twins stretch their AL Central lead.

6. William Contreras, C, Brewers
How acquired: trade with Braves, A’s

Contreras made the NL All-Star team and recorded 20 homers with an .860 OPS over 97 games as Atlanta’s backup catcher and part-time designated hitter in 2022, but the Braves opted to ship him out in the three-team trade that brought Murphy to the team last December. The move has worked out for the Braves, but Contreras’ contributions -- on both sides of the ball -- haven’t been that far off from Murphy’s.

The 25-year-old Contreras struggled on defense in the past, recording a fielding run value of -12 in 2021-22, but his glove work has been a revelation in 2023 (+8 fielding run value). He has remained a strong performer with the bat, too, hitting .283 with 16 homers, 34 doubles, 73 RBIs and an .814 OPS. Contreras has been a significant offensive upgrade over what Milwaukee had at the position in 2022, when Brewers catchers posted a collective .608 OPS with 12 homers in 618 PAs.

7. Zach Eflin, SP, Rays
How acquired: signed in free agency

Although Eflin had a 4.49 ERA (95 ERA+) over seven seasons with the Phillies, the Rays signed him to the largest free-agent contract ($40 million over three years) in franchise history last December. Their gamble has paid off, with Eflin making a career-high 29 starts and recording a 3.44 ERA, an MLB-best 1.01 WHIP and a 7.48 K/BB ratio over 167 2/3 innings. The right-hander’s contributions have been especially important for a Tampa Bay club that lost starters Shane McClanahan, Drew Rasmussen and Jeffrey Springs for the season and was without Tyler Glasnow for almost two months to begin the year.

8. Trea Turner, SS, Phillies
How acquired: signed in free agency

Turner would have been nowhere near this list a month ago, having recorded a .236 average with 10 homers and a .656 OPS over his first 108 games after signing an 11-year, $300 million contract with the Phils last offseason. However, the shortstop has rebounded in a big way, slashing .375/.415/.776 with 16 homers and 40 RBIs over his past 37 games to help Philadelphia solidify its place in the NL Wild Card race. Despite the rough start to the season, Turner’s numbers on the year -- 26 homers, 27 steals (in 27 attempts), 96 runs scored and a .791 OPS -- look an awful lot like what he produced for the Dodgers in 2022.

9. Nathan Eovaldi, SP, Rangers
How acquired: signed in free agency

Although Eovaldi missed nearly two months with a right forearm strain and has thrown just seven innings combined over three starts since returning, the impact he had on Texas’ rotation earlier this season shouldn’t be overlooked. Emerging as the team’s ace in the wake of Jacob deGrom’s season-ending elbow injury, Eovaldi recorded a 2.69 ERA with 111 K’s in 123 2/3 innings across his first 19 starts before going on the injured list.

10. Chris Bassitt, SP, Blue Jays
How acquired: signed in free agency

In the first year of a three-year, $63 million contract, Bassitt is part of an ultra-durable Blue Jays rotation that has helped the club remain in the Wild Card race despite only ranking ninth in the AL in runs scored. Toronto has used an MLB-low seven starting pitchers this season, and Bassitt leads the club with 185 2/3 innings, posting a 3.78 ERA and a 1.20 WHIP across 31 starts. The 34-year-old has thrown at least six innings and held his opponent scoreless eight times in 2023, tied with the Padres' Blake Snell for the most in the Majors.

Honorable mentions: J.D. Martinez (Dodgers), Teoscar Hernández (Mariners), Taijuan Walker (Phillies), Brandon Belt (Blue Jays), Craig Kimbrel (Phillies), Kyle Gibson (Orioles)