Left-hander DJ Herz has decided to undergo Tommy John surgery, according to a report from TalkNats. Herz was recommended for Tommy John surgery in late March but the report suggests he sought second and third opinions before ultimately deciding to go under the knife. The procedure is likely to keep Herz out of commission through at least the first half of the 2026 campaign, though no specific timetable for his return is likely to be announced until after his surgery.
Herz, 24, was an eighth-round pick by the Cubs back in 2019. While in Chicago’s organization, Herz flashed huge strikeout stuff and fantastic results in the lower minors, including a 40.4% strikeout rate between Single-A and High-A back in 2021. It was always held back by lackluster control and paired with poor results at higher levels of the minors, however, such as when he posted a 20.9% walk rate and an 8.24 ERA in nine starts in his first taste of the Double-A level back in 2022. The lefty’s second stint with Double-A Tennessee went better, though his results still didn’t jump off the page: A 3.97 ERA in 14 starts, with a 14.1% walk rate.
Despite those potential red flags, the Nationals saw enough in Herz to trade for him as part of the package for Jeimer Candelario at the 2023 trade deadline. The southpaw made his big league debut last year and looked quite good in doing so. Across 19 starts in the majors, Herz pitched to a roughly average 4.16 ERA (97 ERA+), but struck out an excellent 27.7% of batters faced while walking a much more palatable 9.4% of opponents. His 8.0% barrel rate allowed was somewhat elevated, leading to an elevated home run rate, but even with that flaw Herz’s peripherals looked excellent. His 3.71 FIP was fourth among rookies with at least 80 innings of work last year, his 3.77 SIERA was sixth, and his 3.26 xERA was second to only Paul Skenes.
It was quite the impressive debut for the young southpaw, though one flaw was Herz’s inability to pitch deep into games. Just four of his 19 starts saw him throw 90 pitches or more, and he failed to complete five innings in eight of his starts. Herz’s overall results in his rookie season were more than enough to put him in the conversation for a regular rotation job with the big league club this year, but any plans for him to join the rotation were scuttled when he struggled during Spring Training with a 6.52 ERA, an 8.2% walk rate, and an 18.4% strikeout rate. Those numbers came in a sample of just 9 2/3 innings, but the results were ugly enough that the Nationals made what seemed like an easy decision to option Herz to the minors.
That option was quickly rescinded in favor of placing him on the injured list, however, suggesting that he had sustained an injury during big league camp. That injury proved to be a tear in his UCL, and Herz will now go under the knife and miss all of 2025, plus at least some of the 2026 season. Fortunately for the Nationals, the club has plenty of other young arms to rely on while Herz is out, including fellow lefties MacKenzie Gore and Mitchell Parker. One other name to watch this year is righty Cade Cavalli, who has been out of commission in recent years due to his own Tommy John surgery rehab but figures to be ready to pitch in the majors at some point this year for the first time since 2022.