The Red Sox still have a lot of work to do this offseason, but they have made meaningful progress addressing a primary need.
So far this winter the Red Sox have made two big league acquisitions, both left-handed relievers. Last month the club signed 37-year-old veteran Justin Wilson, who has 12 MLB seasons under his belt and appeared in 60 games for the Cincinnati Reds in 2024. On Tuesday the club signed Aroldis Chapman, a seven-time All-Star who even at age 36 remains one of the game’s most overpowering arms.
The two immediately become Boston’s top lefties and should help bolster a bullpen that collapsed in the second half and is expected to lose incumbent closer Kenley Jansen. Though more moves are likely, the signings should go a long way towards establishing Boston’s core group heading into the new year.
With the Winter Meetings set to begin in a few days, here’s a look at where things stand.
As of today, the Red Sox bullpen looks something like this.
MLB bullpen: Liam Hendriks, Aroldis Chapman (L), Justin Slaten, Garrett Whitlock, Justin Wilson (L), Greg Weissert, Luis Guerrero, Cooper Criswell
Optionable depth: Brennan Bernardino (L), Cam Booser (L), Zack Kelly, Chris Murphy (L), Zach Penrod (L), Chase Shugart, Josh Winckowski
Boston has five relievers who should be more or less locked in to the big league equation. In addition to Chapman and Wilson, Liam Hendriks should be back after spending all of 2024 rehabbing from Tommy John surgery and Garrett Whitlock is also expected to be ready for Opening Day after undergoing elbow surgery in late May. Those four will join Justin Slaten, who was phenomenal as a rookie and projects as one of the club’s top arms again.
In addition to those five, we can surmise that one bullpen spot will go to a long relief/mop-up man. For now we’ll say that’s Cooper Criswell, though he could conceivably also start the season in the Triple-A rotation too.
That leaves two spots up for grabs, and the Red Sox have nine pitchers on the 40-man roster with minor league options who could conceivably compete for those jobs. Realistically all of them will cycle through at one point or another, but for our purposes let’s go with Greg Weissert and Luis Guerrero. Weissert was dominant after being called back up from Triple-A, finishing the season with 17 consecutive appearances without allowing an earned run, and Guerrero didn’t allow an earned run in any of his first nine MLB appearances following his September debut.
If there’s one phrase that sums up the Red Sox pitching philosophy under Craig Breslow, it’s seeking arms who can throw “nasty stuff in the zone.”
The club’s two newcomers certainly have the nasty stuff part down.
Wilson’s numbers from last season don’t exactly jump off the page — he posted a 5.59 ERA over 46.2 innings — but few were better at getting opposing batters to chase pitches. He ranked 95th percentile in chase rate according to Statcast, and with a 95.5 mph fastball he still has the raw tools needed to succeed in the majors.
As for Chapman, his stuff remains elite.
Last season Chapman’s sinker averaged 99.8 mph, his four-seamer 97.8 and his splitter 91.6. He ranked 98th or 99th percentile in expected batting average (.165), fastball velo (98.7) and strikeout rate (37.1%), and those ingredients helped translate to a 3.79 ERA with 98 strikeouts over 61.2 innings with the Pittsburgh Pirates.
For a club that has lagged behind its competition in terms of raw stuff, Chapman will provide some serious gas in the later innings. The problem with Chapman, and to a lesser extent Wilson, is the “in the zone” part of the equation.
Chapman’s 14.4% walk rate was among the worst in baseball last year, and when opposing hitters have managed to make contact against him, they’ve tended to hit him hard. Wilson also hasn’t historically been the most reliable with his command, though last year he posted a career-best 6.2% walk rate.
It also shouldn’t be ignored that Chapman brings significant baggage to the organization as well. In 2016 he was suspended 30 games for violating MLB’s domestic violence policy after being accused of pushing his girlfriend, choking her and firing several gunshots during an incident at his home the prior fall. He’s also had a number of high-profile playoff failures, and in 2022 he was sent home by the Yankees and left off their ALDS roster after skipping a mandatory workout prior to the team’s series against Cleveland.
With Jansen on his way out the Red Sox are going to need a new closer in 2025, and while they have no shortage of candidates, none are a slam dunk.
Hendriks is the top incumbent candidate. Prior to his recent run of injuries and his battle with cancer Hendriks enjoyed a phenomenal four-year run with the Athletics and White Sox, earning three All-Star nods while twice finishing as a top-10 Cy Young vote-getter. He’s been through a lot since then, but if Hendriks can get anywhere close to his old form he could conceivably slot back into the role and lock down the ninth.
Chapman also has extensive experience as a closer. Though he’s primarily served as a set-up man over the past three years, he’s recorded 335 saves in his career and finished the season as Pittsburgh’s closer, locking down nine saves in the month of September after taking the job from David Bednar.
Another who can’t be ruled out is Slaten, who posted a 2.93 ERA over 55.1 innings as a rookie and who was pegged as a potential future closer by manager Alex Cora. Unlike Hendriks and Chapman, Slaten is just entering the prime of his career and could conceivably take another step forward in his second year as a big leaguer.
Last year the Red Sox bullpen finished 24th out of 30 teams with a 4.39 ERA, and starting around the All-Star break the group pretty much fell apart. As currently constituted the Red Sox bullpen should at least be serviceable heading into next season, but there are still question marks.
What can Boston expect out of Hendriks and Whitlock coming off extended layoffs? Will the club’s younger arms take a step forward? Is there enough proven depth to keep things afloat when the injury bug inevitably bites?
To ensure things don’t come off the rails again, the Red Sox should probably still make at least one more impactful addition. Whether it’s signing top lefty Tanner Scott, bringing back veteran Chris Martin or swinging some sort of trade, the Red Sox have learned the hard way what can happen when the bullpen is undermanned late in the season.