Not a lot has gone right for the Boston Red Sox in 2026, who will enter Wednesday night's series finale in Kansas City at 21-27 and in last place in the American League East. However, at least one part of Chief Baseball Officer Craig Breslow's offseason plan has come to fruition: a dominant pitching staff, including a bullpen that has made late-game leads nearly automatic wins. 

After a 2025 season that saw the Boston bullpen finish second in baseball in ERA, the Red Sox 'pen has once again proven it is one of the best in baseball in 2026. Through the first 48 games of the season, the Red Sox 'pen ranks at or near the top of the sport in most categories. Their 3.03 ERA in 184.1 innings pitched ranks second in the league, behind only the Texas Rangers. They also rank in the top five in baseball in WHIP, hits per nine innings, and walks per nine, while finding themselves in the top 10 in WAR, all while having the third fewest meltdowns in the sport. 

The Boston bullpen is, of course, headlined by left-handed veteran closer Aroldis Chapman, who has experienced a career resurgence since signing with the Red Sox ahead of the 2025 season. In 15.2 innings, the 38-year-old has allowed just one run on seven hits while striking out 21 and walking seven, locking down 11 saves, and climbing the all-time saves leaderboard in the process. 

Chapman is supplemented by a duo of Rule-5 righties in Garrett Whitlock and Justin Slaten. Whitlock has quietly become one of the best setup men in baseball. Since the start of the 2025 season, the 29-year-old has the fourth-highest win probability added at 4.35, trailing only Chapman, Padres star Mason Miller, and Braves setup man Robert Suarez. 

Slaten, when healthy, has been equally dominant, posting a 3.14 ERA in 97.1 innings since being acquired in a Rule-5 Draft trade ahead of the 2024 season. In eight innings pitched in 2026, the 28-year-old has yet to allow a run. 

Per Tyler Milliken of the Section 10 podcast, the Red Sox are a perfect 19-0 when leading after seven innings, thanks in large part to the Chapman, Whitlock, and Slaten trio. 

"We're probably the envy of a lot of teams," interim manager Chad Tracy said of the trio when making his weekly appearance on WEEI's Rich and Ken with Ted Johnson show, "to have those three guys, especially when they're all up at once, is a blessing," he continued. 

It hasn't just been the three back-end arms that have been dominant for the Red Sox pen; they have gotten incredibly strong performances from a pair of unheralded lefties, Jovani Moran and Tyler Samaniego. 

After making his major league debut in April, Samaniego looks to be another incredible find for Breslow, allowing just two runs in 16.1 innings, his 1.10 ERA is the eighth-lowest among relievers in baseball. 

While they haven't had many late leads, Tracy can feel more than comfortable that his bullpen is going to lock things down when they do. 

The Red Sox will go for the series sweep of the Royals on Wednesday night in Kansas City. Connelly Early will get the start for Boston opposite Michael Wacha for the Royals. First pitch from Kauffman Stadium set for 7:40 p.m. ET. 

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