The Cubs' Zombie Closer and His Immortal Fastball

[Andres Chavez]

Image courtesy of © David Banks-Imagn Images

The Chicago Cubs might not have their closer, Daniel Palencia, and an army of useful relievers at the moment, but don’t fret: Caleb Thielbar is here. Nobody in the Cubs’ bullpen can replace Palencia’s sheer power and upside, but Thielbar has certainly given fans some peace of mind with his performances out of the bullpen in 2025 and 2026.

The Ageless Wonder

Signed to a one-year deal on Dec. 31, 2024, after a down year with the Minnesota Twins, the superannuated left-hander is reminding us all that age is just a number. Ever since donning the Cubs uniform, he's done nothing but succeed.

Last year, the southpaw posted a 2.64 ERA in 58 innings, with a 3.00 FIP and 1.1 fWAR, his highest output since putting up 1.6 fWAR in 2022. This year, it's been more of the same, from a pitcher whom baseball has tried to get rid of multiple times, and who turned 39 in January.

In eight frames this season, Thielbar has a solid 2.25 ERA and a 3.50 FIP with 11 strikeouts. Since the start of the 2025 campaign, the lefty’s 2.59 ERA ranks 29th among 126 relievers with a minimum of 60 innings pitched.

This weekend, Thielbar notched a save on Saturday and a win on Sunday against the Mets. Evidently, the manager completely trusts him in late-inning situations, and that’s the whole point with high-leverage relievers. Skippers want arms they can trust with games on the line, and he is very much one of them. Thielbar came to Chicago with just four career saves, but he had one last year, has one this year, and could easily collect another 10 or more before Palencia is back.

Since landing in Chicago, Thielbar has taken his game up a notch. Before his 5.32 ERA season in 2024, the number ranged between 3.23 and 3.49 from 2021 to 2023. Now, his ERA starts with a 2, and he's throwing harder than ever, with a 93.6 mph average fastball velocity. In fact, he throws about 4 MPH harder now than he did when he first broke into the majors in his 20s, well over a decade ago.

An Elite Fastball Leads The Way

The pitch earns a very solid 23.4%whiff rate, and has been Thielbar’s bread and butter. It's averaging a whopping 20.2 inches of induced vertical break (IVB), the fifth-best mark among MLB pitchers this year, and yielding an elite .160 xwOBA. It’s no wonder he's increased its usage to 52.4% this year, because hitters just can’t touch it.

While it’s true that Thielbar uses his four-seamer more often than any other pitch, he also has whiff rates of at least 25% with each of his additional offerings: curveball (25%), sweeper (28.6%), and slider (33.3%).

Remember, the guy is 39 years old—or, forget it. Maybe that's the healthier approach. If a pitcher 10 years his junior were doing what Thielbar has done for most of the last half-decade, with this kind of stuff and the trend arrows pointing in the right direction, you'd have no compunction about letting him take on a relief ace role. The Cubs have to be ecstatic with his recent performance, as they have an elite reliever on a salary that better fits a spare part.

Thielbar is proof that players can successfully extend their careers with discipline, work ethic, and an understanding of the science of pitching. It’s fair to wonder where the Cubs’ bullpen, which ranks 21st in baseball with a 0.0 fWAR, would be without Thielbar. He offers solutions to his manager, who knows he is death to lefty hitters but can also get right-handers out if needed. Over the next few weeks, he's likely to be the team's go-to guy, though he really is 39, so the team will use him a bit more judiciously than they might use a younger pitcher with the same stuff. After all, in baseball, no one's actually immortal.

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