DJ Herz activated Monday vs. Tigers in first MLB outing since Sept. 2024

DJ Herz is back. The Nationals announced that the left-hander is being activated off the 60-day injured list to start Monday's game against the Tigers at Comerica Park — his first appearance on a major-league mound since September 25, 2024, a stretch of almost exactly two years.

What happened

Per the club's announcement, Herz is set to take the ball Monday against Detroit, with the Nationals also optioning left-hander Jared Simpson to Triple-A Rochester to open the active roster spot. Washington still needs to create additional space for Herz on the 40-man roster, per Mark Polishuk at MLB Trade Rumors, so at least one more roster transaction is expected before first pitch.

The road back was neither short nor straight. Herz sprained his UCL during Spring Training 2025, which led to Tommy John surgery and cost him the entire 2025 season. When he finally began a minor-league rehab assignment this year, a flexor strain emerged three starts in and pushed the timeline back further. He returned to action for good at the start of August, and his most recent outing for Triple-A Rochester — 65 pitches, 4 1/3 innings, one run allowed — appears to have been the performance that cleared the way for Monday's activation.

MLB Trade Rumors notes the Nationals will probably limit Herz to roughly that same pitch count in his first outing back, which is about as cautious a reintroduction as you can script for a pitcher who has spent the better part of two years working his way back from two separate arm setbacks.

Why it matters

When Herz last pitched in the majors, he was wrapping up a rookie season that gave Washington genuine reason for optimism. That final outing — five innings in a 3-0 loss to the Royals — was the 19th start of a campaign that positioned him as a potential building block for a rebuilding club. The injury that followed put that trajectory on hold, not on ice permanently, and Monday represents the moment the Nationals find out whether the building block is still there.

There is also a broader organizational subplot here. Two days after Josiah Gray made his first MLB appearance since April 2024 — Gray having navigated his own Tommy John surgery and flexor strain — Herz is following the same path back to a big-league mound. Per MLB Trade Rumors, the peace of mind from these late-season returns is expected to help both pitchers enter the offseason with rotation aspirations for Spring Training. The newly extended Cade Cavalli is projected to sit atop the Washington rotation in 2027, with Connelly Early and Andrew Alvarez also in the mix, per the report — meaning Herz and Gray are pitching for spots, not just innings.

The Cavalli extension itself was reported just days ago, with multiple reporters noting Washington and the right-hander were nearing a deal that buys out at least one free agent year. That context makes these late-season auditions from Herz and Gray more than ceremonial: the rotation picture around Cavalli is still being drawn.

The numbers

Herz's rookie season line offers the clearest baseline for what Washington is hoping to see again. Across 88 2/3 innings in 2024, he posted a 4.16 ERA, a 27.7% strikeout rate, and a 9.4% walk rate — numbers that, per MLB Trade Rumors, seemed to line him up as a legitimate piece of the rebuild before the UCL sprain intervened.

In seven rehab outings since returning to action at the start of August, Herz carries a 4.00 ERA over 18 innings. That is a small sample against minor-league competition, but it is the only live-game data available from the post-surgery version of Herz, and it was apparently enough for Washington to feel comfortable handing him a major-league assignment.

Where the club stands

Washington is 73-83 (.468), sitting fourth in the NL East, 19 games back in the division, and eliminated from both the division race and the Wild Card race. The club enters Comerica Park on a one-game losing streak. With the season winding down, the Detroit series — Monday through Wednesday — is less about standings movement and more about the kind of organizational inventory-taking that defines a September for a rebuilding club. Herz is listed as the probable starter Monday against River Ryan. Jackson Kent is projected to start Tuesday against Drew Anderson, and Wednesday's starter for Washington is listed as TBD opposite Framber Valdez.

What we don't know yet

The 40-man roster move required to complete Herz's activation had not been announced at the time of the MLB Trade Rumors report, so at least one additional transaction is pending. It is also worth noting that while the Nationals will reportedly target roughly 65 pitches for Herz on Monday, what comes after that outing remains open. Per MLB Trade Rumors, if things go well, he might be able to make another start — or possibly a bullpen appearance — before the 2026 season concludes. Neither outcome is guaranteed, and the club has not committed to a specific plan beyond Monday.

On the contractual side, MLB Trade Rumors notes that Herz has accumulated almost two full years of MLB service time during his elongated stay on the 60-day IL, but will still finish 2026 short of the threshold required for Super Two status. MLBTR contributor Ethan Hullihen currently projects this year's Super Two cutoff at two years and 134 days of service time. The report characterizes this detail as likely secondary to Herz himself compared to the relief of simply returning to a major-league mound — a reasonable framing for a pitcher who has spent two years waiting for exactly this moment.

What to watch

The obvious question Monday is how Herz's stuff plays against major-league hitters for the first time since that September 2024 outing in Kansas City. The Nationals have been transparent that they expect to keep him around 65 pitches, so the more telling data points will be the quality of contact, the strikeout and walk rates relative to his 2024 baseline, and whether the arm responds cleanly to the workload.

Beyond Monday, watch for Washington to clarify the 40-man roster move and whether Herz earns a second appearance before the season ends. With Gray already back and Cavalli's extension reportedly in place, the final weeks of 2026 are functioning as an extended look at what the 2027 rotation depth might actually be — and Herz, healthy and pitching again, is the most consequential variable still being evaluated.