Aroldis Chapman Is Beating the Odds and Pitching at His Best
Aroldis Chapman is inching closer to 40 years of age, but that hasn't stopped him from pitching like one of MLB's most elite closers in 2025.
Boston Red Sox reliever Aroldis Chapman is doing things that, frankly, have hardly ever been done before. As a rookie throwing unheard-of levels of velocity with his fastball, one would have predicted he’d have a short career doing so before transitioning to either a post-playing career or a pitch arsenal focused on break over velocity.
However, Chapman is still out here throwing some serious heat at age 37 for the Red Sox, who inked him to a one-year, $10.75 million contract this past offseason. He’s notched over 350 saves, over 1300 strikeouts, and has a career 2.55 ERA across more than 800 career innings, and he continues to defy expectations with every passing season.
In 2025, Chapman is not only one of the most effective relievers in all of baseball, but he’s also pitching what might end up being his best season in MLB. How does he keep doing this and how much longer can he keep it up?
All stats updated prior to games on Wednesday, August 6
Symbolic of Red Sox’ 2025 Success
Chapman’s Baseball Savant page is truly a thing of beauty, filled with red bubbles indicating upper-90’s percentile ranks among MLB pitchers. He ranks within the 91st percentile in chase rate (32.4%); 99th in expected ERA (2.10) and expected batting average against (.171); 98th in average fastball velocity (99.1 MPH) and whiff rate (37.8%), and, of course, 100th percentile in strikeout rate (38.7%).
In the latter of these statistics, Chapman leads the league and stands just behind fellow closer Mason Miller, now of the San Diego Padres, who has a strikeout rate of 38.8%. Chapman was signed to a one-year deal for the 2025 season and was seen as a potential trade chip come the July 31st trade deadline this year, but Boston’s refusal to move him proves symbolic of the team’s playoff ambitions for 2025.
Chapman has a 1.21 ERA as of August 6 over 44.2 innings of work in which he has struck out 65 batters and walked only 13. He earned his 8th All-Star selection this season, pitching a scoreless bottom of the 9th inning for the American League. Only three other primary relievers have received more All-Star nods, and they’re some of the best relief arms in baseball history: Mariano Rivera (13x), Craig Kimbrel (9x), and Rich “Goose” Gossage (9x).
When the Red Sox traded third baseman Rafael Devers to the San Francisco Giants earlier this season, many believed that this would signify a selling season in Boston where they would look to rebuild around their young core and sell off veteran players. Chapman would’ve been at the top of that list as a 37-year-old rental arm, but the team’s performed very well in 2025.
With a record of 64-51, the Red Sox sit just 3 games back of the Toronto Blue Jays in the AL East division and were represented at the All-Star game by three players, one of which was Chapman. They are 38-19 at their home stadium in Fenway Park this season, and Chapman has been borderline unhittable there.
Cuban Missile in the Clutch
Chapman has appeared in 24 home games in 2025 for the Red Sox and he’s notched a 0.81 ERA across 22.1 innings. His rate stats across these games are outlandish, as he boasts a 3.63 H/9, 12.49 K/9, and 0.81 HR/9 with 11 saves at home this season. Park Factor rates Fenway Park as the second-most hitter-friendly ballpark right behind Coors Field in Colorado, so Chapman’s excellent performance at home is equally appreciated and impressive.
Better yet, Chapman’s numbers against division rivals stand even more impressive than his numbers at home. Against the Blue Jays, Orioles, Rays, and Yankees this season, Chapman has not allowed an earned run across 12.1 innings, striking out 21 batters and walking one. He’s locked down 7 intra-division saves across 14 outings and has an almost unbelievable 2.92 H/9 rate across these games.
The best way to analyze Chapman’s elevated success across important games this season is to look at his games against teams that are at or above the .500 mark in 2025. He’s pitched 29 innings over 31 games against these teams and is sporting a 1.24 ERA and a 0.621 WHIP while securing 14 saves for the Red Sox against strong opponents.
The Red Sox are already getting incredible performances from the likes of their ace Garrett Crochet and Lucas Giolito, but Chapman’s resurgence is just the cherry on top for a pitching staff that has been dominant in 2025. He’s currently second in the AL in fWAR among relievers with 1.7 (Cade Smith has 1.8), not to mention while being several years older than the rest of the competition.
Control Issues No More?
What’s most impressive about Chapman’s performance this season is the apparent disappearance of his control issues. He has always struggled with finding the strike zone consistently, posting a walk rate of over 14 percent in each of the last three seasons. But in 2025, it’s 7.9%, which is the lowest it’s ever been in his career. For his whole career, Chapman’s incredible fastball velocity came at the cost of throwing consistent strikes, but this year he seems to have found a solution.
And this solution isn’t really coming at the expense of his great velocity, still boasting a 98th percentile fastball velocity in 2025. His sinker, which he throws 33.8% of the time, is chalked at an average of 99.8 MPH, making it the fastest sinker in the league, tied with Daniel Palencia of the Chicago Cubs.
He’s got a 48.4% strikeout rate with his sinker, making it one of the deadliest pitches in the league this year. This is by far the highest strikeout rate of any sinker in the MLB (minimum 100 pitches) and is ahead of second-place Cade Povich of the Orioles in this stat by 13.4%, roughly the same difference between King and 32nd-ranked Taijuan Walker of the Philadelphia Phillies.
Since June 1st, Chapman has a BB/9 rate of just 2.08, miles below what it has ever sat for a full season in his MLB career. It’s 2.6 on the 2025 season as a whole, which also would be a career-best rate. With an arsenal like Chapman’s that now includes a devastating 91.6 MPH splitter, he’s once again bidding for the title of best closer in baseball.
While he isn’t the only guy consistently throwing over 100 MPH anymore, Aroldis Chapman is still one of the most effective relievers in the game at the age of 37. Father Time doesn’t seem to have any effect on him this season, and the Red Sox look like geniuses for taking a flyer on the veteran left-hander with how he’s performed in 2025.
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Ethan has been writing for Jays Journal, a site on the Fansided network, since 2023 and is fascinated by how sabermetric statistics can assist our understanding…