The Boston Red Sox bullpen has been great this season. The unit has consistently kept the Red Sox in games and held leads, and is a big factor in their postseason contention.
The story of the 'pen has been Aroldis Chapman's revival. The 37-year-old closer has been utterly dominant and went a stretch of 50 straight batters without allowing a hit.
While it's been great to have a dominant closer, his setup man is having an incredible season in his own right. Garrett Whitlock embraced a full-time bullpen role this season and has returned to the version of himself the Red Sox got back in 2021. The 29-year-old currently has an ERA under 2.50 in 65.1 innings. He's been worth 2.0 bWAR and has only allowed two earned runs since the start of July. While Chapman has been the Red Sox's Batman, Whitlock has easily been his Robin.
The Sox are no strangers to a good reliever season, but Whitlock's is certainly up there with some of the best non-closer seasons in recent memory. Here are the Red Sox's best non-closer seasons since 2010:
We don’t talk about how nasty Garrett Whitlock has been enough. Sadly the cost of being in the same bullpen as Aroldis Chapman. pic.twitter.com/XoGICE4AHn
— Tyler Milliken (@tylermilliken_) August 26, 2025
Ranking the top non-closer season's for the Red Sox since 2010
1 - Chris Martin, 2023
In 2023, Martin was Kenley Jansen's setup man, and he was lights out. He posted a 1.05 ERA in 51.1 innings, had an ERA+ of 434, and racked up 3.2 WAR (in 2025, Chapman has 3.3). Martin was so good that he received a Cy Young Award vote that season. No other non-closer (and most closers) have had a season that good in a Red Sox uniform.
2 - Daniel Bard, 2010
In 2010, Daniel Bard was the setup man for Jonathan Papelbon, and the eighth inning was almost always locked down. Bard posted a 1.93 ERA in 73 outings, had a 227 ERA+, and had a 3.1 WAR. In 46 appearances from the beginning of May to the end of August, he allowed just seven earned runs. While it wasn't quite what Martin did in 2023, it's easily the second-best out of all.
3 - Garrett Whitlock, 2021
While 2025 Whitlock has been amazing, 2021 Whitlock was a step above. He posted a 1.96 ERA and had 2.8 WAR. While he only made 46 appearances, all out of the bullpen, he pitched 73.1 innings. In 31 of his 46 outings, he recorded more than three outs; 18 of those were six outs or more. Alex Cora consistently relied on him to keep the game close for multiple innings, multiple times a week, and he rarely disappointed.
4 - Garrett Whitlock, 2025
Whitlock is the only reliever to show up on this list twice. While most of the others on this list had other good seasons, no other has had two incredible seasons in Boston like Whitlock. Following a foray into the rotation for a few seasons, he went back into the bullpen, and while he hasn't been the multi-inning guy like he was in 2021, he has settled nicely into a complementary role to Chapman.
5 - Craig Breslow, 2013
While everyone remembers the legendary season Koji Uehara had as the closer of the 2013 Red Sox, Breslow was also very good. Breslow poasted a 1.81 ERA in 61 appearances, while racking up 1.5 WAR. His second half was lights out, too; he only allowed two earned runs from the All-Star break through the end of the season, and nine of his 10 postseason outings were scoreless.
6 - Alfredo Aceves, 2011
Aceves' 2011 is similar to Whitlock in 2021, he was mostly a multi-inning reliever, but he mixed in four (pretty bad) starts. Ultimately though, the righty racked up a 2.7 WAR over 114 innings (93 out of the bullpen), and ended the season with a 2.61 ERA. His high innings total certainly helped him bring that WAR up, but still, he only allowed 21 earned runs out of the 'pen in 51 appearances.
7 - Burke Badenhop, 2014
The journeyman reliever joined the Red Sox in 2014 and was extremely solid. His 2.29 ERA in 70 appearances was the lowest of any reliever on the team with 50 or more appearances. He had a 1.5 WAR, second only to Koji Uehara. 2014 was Badenhop's only season in Boston, and it was the best season of his eight-year career.
8 - Junichi Tazawa, 2012
Tazawa was dominant for the 2012 Red Sox. He had a 1.43 ERA and an ERA+ of 296. He was worth 1.7 WAR that season. The reason he is so low on this list is that he spent all of May, June, and half of July in Triple-A Pawtucket, despite not allowing a run in his five April outings. Had he spent the entire season on the roster, he could have been right at the top of this list.