BOSTON — The Red Sox bullpen is going to look a whole lot different in 2025, but after a catastrophic collapse down the stretch it should be better equipped to handle the rigors of a full season.

With two outside additions and two key arms set to return from injury, the Red Sox go into the new year with a core of five relievers along with a deep pool of arms who will likely cycle back and forth between Boston and Worcester. Given that the Red Sox are expected to carry six starting pitchers — meaning one fewer bullpen spot — the club will have to lean on that depth while also heavily emphasizing relievers who can pitch multiple innings at a time.

So who’s a lock, who could compete for the closer spot and who faces the toughest competition heading into camp? Here’s a look at how the Red Sox bullpen stands today.

Veteran relievers

Liam Hendriks: After spending 2024 completing his recovery from Tommy John surgery, Hendriks is expected to make his Red Sox debut this spring. A three-time All-Star, Hendriks is one of Boston’s most accomplished relievers and figures to be the favorite to earn the closer job out of camp, but after two years lost to cancer and elbow surgery, it remains to be seen if Hendriks can still be the same guy who recorded 37 saves for the White Sox in 2022.

Aroldis Chapman: One of Boston’s first offseason signings, the 36-year-old Chapman has recorded 335 career saves but has mainly pitched as a set-up man over the past few seasons. The left-hander remains one of the hardest throwers in the game and figures to give the Red Sox the kind of late-inning heat the bullpen has lacked in recent years. He will also be a candidate to close if Hendriks struggles in camp.

Justin Wilson: A 37-year-old left-hander, Wilson boasts an average fastball velocity of 95.5 mph and a chase rate that ranks 95th percentile in MLB. He’s also good at avoiding walks, and while his numbers in Cincinnati last year weren’t great (5.59 ERA in 46.2 innings), the Red Sox believe he still has the tools to be an effective left-handed weapon if used correctly.

Multi-inning weapons

Garrett Whitlock: With the Red Sox expected to carry six starting pitchers, the club will have to make do with one fewer bullpen spot. That will make guys like Whitlock essential, as their ability to pitch multiple innings in high-leverage situations will both take pressure off the other relievers and open other possibilities for Alex Cora. Whitlock has already thrived in this role, and if he can stay healthy he could prove to be the key to the whole group’s success.

Justin Slaten: Like Whitlock, Slaten is a former Rule 5 pick who immediately thrived upon his arrival in Boston. Last year Slaten was arguably the most important member of the bullpen and as soon as he went down in July the whole group fell apart. Slaten could be a contender for the closer job, but more likely he’ll serve a similar role as Whitlock, giving the club two multi-inning weapons who can help make up for the club’s comparative lack of numbers.

Optionable depth

Greg Weissert: Besides having guys who can pitch multiple innings in close games, the Red Sox can also make up for having one fewer bullpen spot by leaning on their deep pool of relievers who can bounce back and forth from Triple-A. One of the favorites to make the Opening Day roster from this group should be Weissert, who finished last season with 17 consecutive appearances without allowing an earned run.

Luis Guerrero: Guerrero was fantastic following his September promotion, going nine straight appearances without allowing an earned run. The rookie right-hander boasts a 97.5 mph fastball and should be another top contender to start the season on the Opening Day roster.

Cooper Criswell” Criswell was quietly one of the MVPs of the Red Sox staff last season, pitching effectively both as the club’s No. 5 starter and as a bulk reliever. Criswell probably won’t be relied upon to start this year, but his ability to pitch multiple innings while bouncing back and forth between Boston and Worcester will make him invaluable.

Zack Kelly: Kelly boasts overpowering stuff and at times was among Boston’s most dominant relievers, but he’s also struggled with consistency. When Kelly is good, he’s one of the best pitchers the Red Sox have, but whether or not he can avoid the occasional meltdown will determine how big a role he ultimately plays.