Who Should Be the Red Sox Closer in 2025?

The Boston Red Sox rosters of the 21st century have had some all-time great closers occupy the ninth for them, with names like Jonathan Papelbon, Craig Kimbrel and most recently Kenley Jansen picking up saves for them in the recent past.

But now that Kenley Jansen has hit free agency, the Red Sox have some uncertainty surrounding who will anchor their bullpen in 2025.

Now that’s not to say that the Red Sox don’t have any options to close out games for them this season.

In fact, there are a few options that manager Álex Cora has at his disposal to take the ball in the ninth, with former premier closing options: Liam Hendriks and the recently-signed Aroldis Chapman, as well as a breakout star in 2024: Justin Slaten.

So with multiple options to choose from, which of these three should assume the closer role for the Red Sox in 2025?

What Red Sox Closer Candidates Bring to the Table

Liam Hendriks

Hendriks has some elite years as closer under his belt between from 2019-2022, which he split between the Oakland Athletics and the Chicago White Sox.

His final two years with the A’s (2019-2020) saw him assume the closer’s role, where he posted sub-2.00 ERAs, sub-1.00 WHIPs, sub-.200 AVGs as well as K/9 totals above 13.00 in each season, with 25 saves in 85.0 innings in 2019 and 14 saves in 25.1 innings in the COVID-shortened 2020 campaign.

Then after signing with the White Sox ahead of the 2021 campaign, he posted back-to-back seasons with a sub-3.00 ERA, a WHIP at or near 1.00, a sub-.215 AVG against, and 30+ saves in both 2021 and 2022

And his strikeout stuff ticked up after the move to the southside as well, as he posted his two highest K/9 totals of his career those seasons with a 14.32 total in 2021 and a 13.27 total in 2022.

But 2022 was the last year that Hendriks has been able to consistently pitch. In 2023 he pitched in just five innings due to missing time undergoing cancer treatment and then requiring Tommy John surgery upon his return to the White Sox bullpen.

His recovery from Tommy John also saw him miss the entirety of his first season as member of the Red Sox in 2024.

When Hendriks is healthy he’s an elite strikeout reliever, as he’s never ranked below the 97th percentile in strikeout rate in his last four complete seasons (2019-2022), with a 95+ mph fastball with strong whiff-inducing breaking pitches with his slider and his curveball.

Aroldis Chapman

There have been few closers in MLB history who have been as fear-inducing as Chapman.

He’s always been known for his electrifying fastball, which even at age 36 still averages in the upper 90s and occasionally touches triple digits.

And in terms of a track record as a closer, Chapman has a sterling resume, as in the eight seasons from 2012-2019, split between the Reds, Cubs and Yankees, he posted a sub-3.00 ERA, K/9 totals above 13.00 and 30+ saves in seven of the eight season, and a sub-1.15 WHIP and a sub-.200 AVG against in all eight campaigns.

But Chapman hasn’t been a regular closer since 2021, and while his strikeout numbers have always remained high, his walk rates have spiked in recent years, as he went from having just one season since with a BB/9 total above 5.00 from 2012 to 2020 to four consecutive seasons with BB/9 rates above 5.50 from 2021 to 2024.

When Chapman is on he can be one of the league’s elite ninth inning guys, but when he struggles we’ve seen just how far he looks from that fear-inducing arm he consistently was in his prime.

Justin Slaten

Then there’s Slaten, who went form a Rule 5 Draft pick last winter, to a key late-inning reliever out of the Red Sox ‘pen in 2024.

Slaten was a excellent in first taste of big league action, posting a 2.93 ERA, a 2.61 FIP, a 1.01 WHIP and a .221 AVG against in 55.1 innings.

He managed decently high strikeout rates, with his 25.9% posting ranking in the 72nd percentile of league arms. And he paired that with an extremely impressive walk-rate, posting a 4.0% total which placed him in the 97th percentile.

He also sports a diverse pitching arsenal, as his four-pitch mix includes three pitches that saw opposing hitters’ AVG fall below .250 and SLG below .355 against them.

It can be a difficult task for a Rule 5 pick to have immediate staying power beyond their mandatory one-year of MLB service time upon being drafted, but Slaten not only stepped up to occasion, he excelled and played a huge part in the Red Sox improvement in 2024.

That being said, we have to keep in mind that this is still a small major league sample size for the 27-year-old righty, and relief pitching is arguably the most volatile position in baseball.

Who Should Take Over the Ninth?

The Decision

Now that the cases for each of the frontrunners for Boston’s closing role have been laid out, it’s time to answer the question: who should close games for the Boston Red Sox in 2024?

I feel the answer should undoubtedly be Slaten.

Slaten did everything particularly well. From strong surface level stats to solid underlying metrics, he was at minimum above average across the board in 2024.

As per Baseball Savant

I’ve stated already that the biggest red-flag when it comes to Slaten is the fact we only have one year of MLB service time to gauge our opinions off of. But that seems to be the only glaring red-flag he has working against.

Maybe his cutter (his primary offering) could due with some work to lower opposing hitters AVG of .247 down a bit. And maybe his sweeper (his third most utilized pitch) isn’t all that effective at the moment. And maybe his xBA isn’t anything spectacular.

But at the end of the day those are all relatively small issues for an arm that was tested with his first taste of big league ball, with the odds stacked against him as a Rule 5 selection, in one of the biggest markets in MLB, and passed with flying colors.

He has a four pitch mix, with two very impressively rated pitches (his cutter and his four-seam fastball) at the forefront, he strikes out hitters at good clip, walks them at very low rate, and seems to limit hard contact.

And when you compare him to the other two arms vying for the closers role, his limited red-flags are a lot less worrisome in comparison.

Hendriks will be 36 on Opening Day and has played just 5.0 innings since 2022.

And when we isolate his four-year window as a closer (2019 to 2022) he struggled in that time to limit hard contact against him. His hard-hit ranked below the 40th percentile in three of those four seasons, and he posted AVG exit velocity totals in the 25th percentile or lower in every one of those four years.

And shifting to Chapman now, despite helping out the Pirates in a big way in 2024 amidst their closer David Bednar’s struggles, the fact remains that Chapman hasn’t been a team’s primary closing option since 2021.

And in that 2021 season with New York, we saw some of the glaring flaws get exposed. His walk rate jumped from 3.09 BB/9 in 2020 to 6.07 BB/9 a year later. Issuing free passes has always been an issue for Chapman but in recent years he’s been exceptionally bad when it comes to his control, walking hitters more than 14% of the time in the last four seasons.

The other thing to take into account is the fact that not only is Slaten significantly younger than Hendriks and Chapman, he still has five years of team control left, giving the Red Sox a real opportunity to mold themselves a closer for the future, compared to their two veteran options who will likely both hit the open market in their late 30s at the end of the of the season.

Can Slaten Handle Closing Duties?

Now to determine whether Slaten is up to the task of handling the ninth inning for the Red Sox moving forward, let’s compare him to one of the better closers in the past few seasons: Tanner Scott, who I thought should’ve been an option for the Red Sox at the beginning of the offseason in an earlier article, but after signing of Chapman I feel they have their bullpen’s backend-mix solidified.

In the last two seasons among qualified relievers, Scott holds the highest combined fWAR total, the fourth highest ERA and the ninth highest AVG against.

Now I want to clear here, I’m not advocating Slaten is in the same caliber of arm as Scott at the moment. Scott has been one of the league’s premier relievers for a few years now, and again, Slaten is coming off his first year in the majors.

But if we put Scott and Slaten’s 2024 seasons up against each other there are a lot of similarities that lead me to believe a guy like Slaten can develop into a great closing option, like Scott, down the road.

Both featured solid-to-great swing-and-miss capabilities last season, with Slaten having even more promise in past seasons in the minor leagues. And Slaten actually did something in 2024 that Scott didn’t: limit walks.

And from a batted ball standpoint both induce a lot of medium contact while limiting hard hit rate to at least an above average degree, with both sitting in the upper third of league arms in hard-hit rate, according to Baseball Savant. They also each keep the ball on the ground at a high rate, another feather in Slaten’s closing cap.

And from a pitch mix standpoint, Scott features two excellent pitches with his four seam fastball and his changeup.

While Slaten may not have any pith as dominant as Scott’s four-seamer, he features a more diverse arsenal with three positively rated pitches.

Now this is just one comparison, but the point I’m trying to get across here is that there are plenty of elements to his game that stack up well against the established big league relief arms.

Slaten is a well-rounded reliever who has the makings of being a reliever that can not only last but can do it to a high degree moving forward.

And with the veteran presence of two experienced closers behind him in Hendriks and Chapman, the Red Sox have a bit of safety net to make this experiment a no-brainer to try in 2025.