Red Sox Offseason Bullpen Primer: Continuity Is Key, Even Through Injury and Age-Related Concerns

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On June 20, it seemed certain that the Boston Red Sox would be sellers at the trade deadline. A fire sale seemed imminent, and it felt like a foregone conclusion that All-Star closer Aroldis Chapman would be moved, among other pieces.

But then, the improbable happened. There was a historic win streak, an infusion of magic to a season that seemed bleak at best. The Red Sox secured a playoff berth before sputtering out in the Wild Card Round.

But the potential trade chips remained on the team including Chapman, the cornerstone of the Red Sox bullpen. That unit was a constant source of optimism through an up-and-down season. A 3.00 ERA and a 1.17 WHIP were good for league-leading marks and complemented one of the league's best rotations.

But what will the relief corps look like in 2027? With Chapman and newfound star Tyron Guerrero reaching their age-39 and age-36 seasons, respectively, and ever-present injury concerns, there are plenty of questions needing answers.

Red Sox's Bullpen Outlook: The Positives

The Red Sox's bullpen is a terrific unit, and that should keep up in 2027. A well-rounded group as is, the Red Sox aren’t candidates to go out and sign a big name.

And with the returns of Garrett Crochet, Johan Oviedo, Tanner Houck, and Kutter Crawford expected next year, the relief corps' workload should let up. With a surplus of rotational talent, it wouldn’t be surprising to see a couple of those names in the bullpen at least to start the season.

Chapman has proven that he’s still a top-five closer in the game, even as he approaches his 40s. A 1.92 ERA ranked 10th among all relievers, and his 35 saves were tied for third-most across the league. His $13-million option vested at the end of the season, and while durability could be an issue, Chapman will provide late-inning stability as Boston’s closer.

But before teams face Chapman, they need to get through Garrett Whitlock first. A brutal 1-2 punch, the two combined to shut down teams all season long. The righty Whitlock held opposing batters to a 1.72 ERA and walked just nine all season. With a $8.25-million club option, Boston’s dynamic duo will be back to haunt hitters throughout 2027.

Then you have Guerrero, who emerged as a dependable piece down the stretch, showcasing his flame-throwing capabilities. However, he’s entering his age-36 season, and with a slim major-league sample size, it’s yet to be seen if that success is sustainable across an entire season.

Erik Miller was acquired from San Francisco in exchange for former top prospect Marcelo Mayer. He began his Red Sox tenure with questions about his control, but seemed to quiet them with some early success. But as the season dragged on, the concerns resurfaced; Miller was shaky at best, posting a 7.36 ERA and limping through his final few outings of the season. But he’s proven that he can be a valuable part of the pen and will return to a middle-innings role with a $1.5 million projected paycheck in 2027.

Jovani Moran and Greg Weissert weren't always consistent throughout the season, but they pitched well when it mattered and will return to similar roles in 2027. Moran posted a 3.15 ERA and held batters to a .153 average. His walks were a point of concern, however, posting a 4.25 BB/9 mark.

Despite being inconsistent in high-leverage situations, Weissert was leaned upon heavily throughout the 2026 campaign. His 3.26 ERA isn’t ugly, but his 3.96 FIP tells a slightly different story. If he finds stability in clutch moments, his role would increase significantly, but until then it seems like he’ll fit in where most fans want him to: low-pressure situations.

Justin Slaten faced similar struggles in clutch moments, compiling a 4.60 ERA across 36 games. He struggled with elbow issues all year long, similar to the two prior seasons. He posted a 2.93 ERA in 44 games in 2024, but hasn’t seen the same levels of success since. He occupies a precarious position, but he should pitch in a low-leverage role to start.

Alec Gamboa was called up towards the end of the season, and pitched extremely well across 21 outings. He ate up innings to the tune of a 1.91 ERA and will certainly see big league time even if he starts the season back in Triple-A.

One of the most intriguing storylines throughout the season was Brayan Bello’s success as a reliever. He pitched the most innings of any Red Sox pitcher out of the bullpen with 63.2, and posted a dominant 1.98 ERA. As a starter, he had an abysmal 10.35 ERA (though he got better later in the year). His role is yet to be determined, but if his form keeps up he would be yet another weapon for Chad Tracy to utilize in the late stages of games.

Red Sox's Bullpen Outlook: The Negatives

There’s no question about it, the Red Sox have the talent to be the best. But whether or not they can weather age and injury will be key.

Slaten has missed significant time over the past three seasons, and Chapman and Guerrero aren’t getting any younger. Guerrero missed the postseason due to shoulder issues, and Whitlock missed time with elbow inflammation as well.

Chapman will be 39 when Opening Day rolls around. While he hasn’t shown many signs of slowing down, there is always fear when it comes to aging players, especially one who relies on velocity so heavily.

The bullpen got hammered by the New York Yankees in the postseason, giving up an ERA over 20.00 with more innings falling to Moran, Weissert, and the rest of the healthy pen. The aforementioned return of various starters will be helpful, but Boston will need healthy seasons all around.

Another reason for concern? The lack of prospects in the pipeline. The minor-league system was severely thinned out after a series of trades. Now, there are four organizational top-20 pitching prospects with a 2027 ETA: John Holobetz, Eduardo Rivera, Blake Wehunt, and Gage Ziehl. Rivera pitched well in two 2026 MLB appearances, but fell apart in a third. The other three prospects aren’t held in extremely high regard, and it seems unlikely that the Red Sox will turn to any unless there is no other option.

Still, the return of established starters will play into Boston’s favor even if the injury bug strikes again. This might not be the best bullpen in baseball, but the Red Sox are poised to keep dominating the late innings with this group.