Article: Breaking Down the Boston Bullpen: Part 1

[Amrit Brown]

The bullpen will be crucial to the Red Sox' success in 2025. This is the first of a five-part series breaking down each reliever's 2024 season and what to expect in 2025.

Relief pitcher is the most volatile position group in baseball. Contracts are smaller, arms are fungible, and transitions from reliever to starter and back are becoming more common. The Red Sox had eight relievers on their Opening Day roster in 2023. Only one of them had been on the Opening Day roster in 2022, and only three of them would be on the Opening Day roster in 2024. Last season, the bullpen’s 4.39 ERA and 4.11 FIP ranked 24th in baseball, while its 613 innings pitched ranked 10th. With newly-acquired ace Garrett Crochet still working his way toward a normal starter’s workload and Lucas Giolito ramping up after missing the entirety of last season, the team will likely need both more quantity and more quality out of the bullpen if it plans on contending in 2025.

With that in mind, this will be the first of a five-part series examining 15 Red Sox relievers from 2024. The goal is to understand where they finished the season in order to get a sense of what the 2025 ‘pen will look like. We’ll start with three of the team’s 2024 bullpen stalwarts.

Greg Weissert
Greg Weissert led all Red Sox relievers with 62 appearances and 63 1/3 innings in 2024. The 29-year-old right-hander is still on a rookie contract and won’t be arbitration eligible until 2026, so his performance and durability during the 2024 season are encouraging signs for the future. Weissert’s 3.13 ERA was second-best among Red Sox relievers, modeling some semblance of consistency out of the pen. However, Weissert’s peripherals indicated some real reasons for concern. This was his first full season in the majors and his 3.76 FIP was more than half a run higher than his ERA, which indicates that he might have benefitted from some good luck. Weissert earned a whiff on just 20% of his pitches, which put him in the 10th percentile. Pitchers who miss bats so infrequently need to be great a inducing weak contact or keeping the ball on the ground, and Weissert didn’t excel in either category. He’ll need to improve in at least one of those three areas if he hopes to keep his success going.

Justin Slaten
Objectively, Justin Slaten was the Sox’ best reliever this year. In his first taste of the majors, he led the bullpen with 1.5 fWAR and a 2.93 ERA, and his 55.1 innings were the second only to Weissert. He was also able pitch more than an inning, racking up his 55 1/3 IP in just 44 appearances. Slaten featured one of the more impressive pitches in baseball this year. Among pitchers who threw at least 30 innings in 2024, his curveball ranked first in Stuff+ with an absurd 158 score. Slaten did just about everything well. His 35% chase rate was one of the best in all of baseball, and he was excellent at missing bats, avoiding hard contact, and keeping the ball on the ground. His 2.61 FIP was even better than his ERA (likely because he was inducing groundballs in front of Boston’s lackluster infield defense). His 4% barrel rate put him in the 96th percentile, just one spot behind Cy Young candidate Emmanuel Clase.

The 27-year-old Slaten won’t enter arbitration until 2026 and he won’t be a free agent until 2029. As with Weissert, Slaten seems like an opening day must for the Red Sox and his strong peripheral stats suggest he could be just as good in 2025.

Chris Martin
In his second year with the Sox, Chris Martin saw his ERA balloon from 1.05 to 3.45. However, he was one of just five Red Sox relievers with a sub-3.50 ERA in more than 10 innings pitched. The good news? Martin’s FIP only rose by .34 and his expected FIP was better in 2024 than in 2023. Furthermore, Martin maintained many of the traits that contributed to his incredible ERA in 2023.

Martin walked just 0.6 batters per nine innings, the least among all 402 pitchers 474 pitchers who threw at least 30 innings. He allowed just five barrels all season, and Stuff+ saw his splitter as elite, giving it an impressive 126 score. So why did Martin’s ERA rise? The problem was twofold for him in 2024. In 2023 he outperformed many of his expected metrics. His 3.18 expected ERA was much higher than his actual ERA. It was almost guaranteed he would regress somewhat this past season. Additionally, in 2024 Martin was extremely unlucky. he posted a .353 BABIP which was eighth-highest among relievers to throw more than 30 innings.

Martin is a free agent and is entering his age-39 season. He’s indicated that 2025 will be his last season, and he’s rumored to be interested in pitching closer to his home in Texas. However, the the 6’8” monster of a man clearly had plenty in the tank in 2024, and the Red Sox could definitely use him. No matter where the righty ends up, expect elite command and expect his underlying numbers to translate to more success than they did in 2024.

This first iteration of the series is pretty cut and dry. Weissert and Slaten are excellent candidates to record serious innings for the squad next year. Martin should be a serious option for the Red Sox to sign in free agency. The next part of the series will dive further into the meat of the pen and will include Chase Anderson, Brennan Bernardino and Zack Kelly.

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[mvp 78]

On 12/30/2024 at 9:02 AM, Amrit Brown said:

Relief pitcher is the most volatile position group in baseball. Contracts are smaller, arms are fungible, and transitions from reliever to starter and back are becoming more common.

 

The problem is that Bloom overly believed in the volatile/fungible nature of relievers so much so that we got a whole bunch of garbage thrown at the wall for 4 years and most of it just didn't work. The prevailing opinion was that arms could pop out of nowhere so what's the point in spending on them. I believe that can be true, but you can't rely on that as a strategy. There are good relievers. However, their stats are impacted wildly by small sample sizes. They could pitch virtually the same year to year to year, but one blowout would make it look like they were awful one season. 

[Old Red]

16 minutes ago, mvp 78 said:

The problem is that Bloom overly believed in the volatile/fungible nature of relievers so much so that we got a whole bunch of garbage thrown at the wall for 4 years and most of it just didn't work. The prevailing opinion was that arms could pop out of nowhere so what's the point in spending on them. I believe that can be true, but you can't rely on that as a strategy. There are good relievers. However, their stats are impacted wildly by small sample sizes. They could pitch virtually the same year to year to year, but one blowout would make it look like they were awful one season. 

Bloom did a good job with Martin, and Jansen even though he was a year late signing Jansen.

[mvp 78]

Bloom pens:

2020: 26th fWAR, 27th ERA

2021: 8th fWAR, 13th ERA

2022: 26th fWAR, 27th ERA

2023: 13th fWAR, 20th ERA

The 2021 pen worked because they had Barnes and Ottavino at the back end with Whitlock adding bulk innings and Taylor being a solid middle reliever. Bloom tried to recreate that in '23 (Martin and Jansen), but was hurt by the additions of Kluber, Barraclough, Ort and Bleier. Some real low end guys in there. 

[5GoldGlovesOF,75]

1 hour ago, mvp 78 said:

The problem is that Bloom overly believed in the volatile/fungible nature of relievers so much so that we got a whole bunch of garbage thrown at the wall for 4 years and most of it just didn't work. The prevailing opinion was that arms could pop out of nowhere so what's the point in spending on them. I believe that can be true, but you can't rely on that as a strategy. There are good relievers. However, their stats are impacted wildly by small sample sizes. They could pitch virtually the same year to year to year, but one blowout would make it look like they were awful one season. 

By now, we shouldn't be so sure Bloom overly believed anything -- except what he was told to do when he was hired to do it.

I'm one of his biggest critics, and trading Mookie will be in his obit, but "a whole bunch of garbage thrown at the wall" has carried over into the Breslow Era, too.

So now we know that a Boston CBO is really only a figurehead at the task end of a major front office mandate (by a front office full of lifers) -- and let's just call it what fans now know as a conspiracy -- to cut corners in an attempt to at least appear to compete.

These guys who run the Red Sox are just way too intelligent with advanced college degrees to all be so incompetent for this many years... and ask yourself this: would a multi-billionaire owner ever stand for it -- for one year -- if he wasn't in on the plan?

[mvp 78]

11 minutes ago, 5GoldGlovesOF,75 said:

By now, we shouldn't be so sure Bloom overly believed anything -- except what he was told to do when he was hired to do it.

I'm one of his biggest critics, and trading Mookie will be in his obit, but "a whole bunch of garbage thrown at the wall" has carried over into the Breslow Era, too.

So now we know that a Boston CBO is really only a figurehead at the task end of a major front office mandate (by a front office full of lifers) -- and let's just call it what fans now know as a conspiracy -- to cut corners in an attempt to at least appear to compete.

These guys who run the Red Sox are just way too intelligent with advanced college degrees to all be so incompetent for this many years... and ask yourself this: would a multi-billionaire owner ever stand for it -- for one year -- if he wasn't in on the plan?

It's not that they are figureheads, it's that they have no control over increasing the budget meaningfully. The days of feeding the Monster are gone and aren't coming back anytime soon. 

Hey, weren't they spending up to the second CBT line this year?

[moonslav59]

10 minutes ago, mvp 78 said:

It's not that they are figureheads, it's that they have no control over increasing the budget meaningfully. The days of feeding the Monster are gone and aren't coming back anytime soon. 

Hey, weren't they spending up to the second CBT line this year?

I kept thinking the days of feeding the monster would cycle back around, one day, but it really has not happened. The Story signing, and to a lesser extent, Yoshida deal didn't even match the amount of salary we have lost over those years. The Devers extension was massive, but it too did not put us near the spending and spending rankings we used to be at, years ago. It was also likely only done to quell a fan revolution.

I will say, that despite these guys being mainly "figureheads," there is still some major disconnect going on within the FO. Are they really this stupid? Are they really just blatant liars? Are the both?

If the Kennedy statement about the tax line not being a priority, this winter was true or close to the truth, then what is the hold up? Is someone saying, "It's okay to spend up to $260M," but then nix every big offer suggested, only because they'd rather spend the money on other players? What "other players?"

Again, it looks like it is not happening. The so-called bidding on Soto was a mirage and fed the idea that our FO is willing to spend, but just on certain players that we never make the top offer on.

I'm tired of the circle jerk. This was the winter for action- meaningful action.

Okay, Crochet was meaningful, but where is the spending to go along with that trade and open up the window wide, even if just for Crochet's 2 years of control?

Cricketts, as always. (Please, nobody say the name "Buehler" as an effort to spend us to glory.)

[mvp 78]

5 minutes ago, moonslav59 said:

I will say, that despite these guys being mainly "figureheads," there is still some major disconnect going on within the FO. Are they really this stupid? Are they really just blatant liars? Are the both?

If the Kennedy statement about the tax line not being a priority, this winter was true or close to the truth, then what is the hold up? Is someone saying, "It's okay to spend up to $260M," but then nix every big offer suggested, only because they'd rather spend the money on other players? What "other players?"

It seems obvious to me that Sam is out there playing a used car salesman role and is trying to get the Red Sox over to the public regardless of what they'll actually do. Is he stupid? No, there's just a disconnect between when he sees himself as in being a caretaker of the Red Sox and what the normal Sox fans want out of the Sox. His wants and needs are different than those of us on here. If the Sox miss the playoffs again, I don't think it impacts Sam the way it impacts us. 

Selling the team to the public is not necessarily the CBO's job and I don't think we've had a guy in that role try to really do that. The CBO is clearly working under fiscal constraints that they really don't comment on and are trying to build an org the way they see fit. Bloom leaned on farm development and kind of ignored the MLB team. Breslow focused a little bit more on the MLB team, but still hasn't been able to push them over the top. 

The real rot of the organization is at the tippy top and largely the reason they weren't a hot destination for potential CBO's to interview at. 

[moonslav59]

7 minutes ago, mvp 78 said:

It seems obvious to me that Sam is out there playing a used car salesman role and is trying to get the Red Sox over to the public regardless of what they'll actually do. Is he stupid? No, there's just a disconnect between when he sees himself as in being a caretaker of the Red Sox and what the normal Sox fans want out of the Sox. His wants and needs are different than those of us on here. If the Sox miss the playoffs again, I don't think it impacts Sam the way it impacts us. 

Selling the team to the public is not necessarily the CBO's job and I don't think we've had a guy in that role try to really do that. The CBO is clearly working under fiscal constraints that they really don't comment on and are trying to build an org the way they see fit. Bloom leaned on farm development and kind of ignored the MLB team. Breslow focused a little bit more on the MLB team, but still hasn't been able to push them over the top. 

The real rot of the organization is at the tippy top and largely the reason they weren't a hot destination for potential CBO's to interview at. 

So, basically a used car salesman= big fat liar.

(BTW, I don't disagree.)

[dgalehouse]

A strong and deep bullpen is pretty much essential in baseball today. I think the Sox really need to improve in this area. They make the playoffs last season if they had not blown so many leads. Chapman and Hendriks should help offset the expected loss of Jansen and Martin. Slaten looks good. And Guerrero is promising. Whitlock ?  I would still like to add a couple of more quality relievers.  Do that and this should be a playoff team. 

[mvp 78]

8 minutes ago, dgalehouse said:

A strong and deep bullpen is pretty much essential in baseball today. I think the Sox really need to improve in this area. They make the playoffs last season if they had not blown so many leads. Chapman and Hendriks should help offset the expected loss of Jansen and Martin. Slaten looks good. And Guerrero is promising. Whitlock ?  I would still like to add a couple of more quality relievers.  Do that and this should be a playoff team. 

Signing one more impact arm could go a long way. 

[notin]

22 hours ago, mvp 78 said:

Signing one more impact arm could go a long way. 

Kyle Finnegan’s agent can be reached at (443) 615-7710…

[moonslav59]

On 12/31/2024 at 12:51 PM, dgalehouse said:

A strong and deep bullpen is pretty much essential in baseball today. I think the Sox really need to improve in this area. They make the playoffs last season if they had not blown so many leads. Chapman and Hendriks should help offset the expected loss of Jansen and Martin. Slaten looks good. And Guerrero is promising. Whitlock ?  I would still like to add a couple of more quality relievers.  Do that and this should be a playoff team. 

I think our pen is deep, and the middle and deeper parts would turn into a big plus, if every RP'er we have was moved down one notch by adding a real closer and two slots by adding a solid set-up man, too. Just adding one might be enough.

Imagine this pen:

Scott- closer

Hoffman, Chapman & Hendriks- set-up

Slaten & Whitlock as 7th inning guys

Crawford & Wink as inning eater/long men

That's a damn good pen that could be had without us going over the tax line.

AAA pen depth: Wilson (out of options) Guerrero, Kelly, Weissert, Penrod, Bernardino, I Campbell, Mata, Shugart/Adams