Kodai Senga's Season Unravels: Back Injury, Velocity Drop, and a Franchise at a Crossroads
Three years ago, Kodai Senga arrived in New York as the Mets' marquee free-agent acquisition — a Japanese ace with a ghost fork that baffled hitters and a 97-mph fastball that announced he belonged. He was everything the Mets hoped for in 2023: an All-Star, a Cy Young contender, the kind of pitcher who makes a rotation legitimate. Now, heading into May 2026, Senga is 0-4 with a 9.00 ERA, nursing a lumbar spine injury, and facing questions about whether he'll ever recapture what made him one of the game's most exciting arms.
The latest chapter is grim. Senga was placed on the 15-day injured list on April 28, 2026, retroactive to April 27, with lumbar spine inflammation. He received an epidural the same day and faces a 7-to-10-day throwing blackout before anyone can even assess where his recovery stands. The prognosis, in Senga's own word: "difficult."
How Bad Has It Actually Been?
The numbers don't lie, and they're brutal. Across five starts in 2026, Senga posted a 9.00 ERA and 1.95 WHIP in just 20 innings. He struck out 23 batters — a reminder of the talent still in there — but walked 13 and surrendered enough hard contact to make every outing a white-knuckle affair for the Mets' dugout.
The collapse accelerated over his final three outings before the IL stint. In that span, Senga allowed 16 earned runs in just 8⅓ innings — an ERA that doesn't fit on a standard baseball card. The last start, April 26 against the Colorado Rockies in a doubleheader, was the final straw: 3 runs in 2⅔ innings before he was pulled, his back too compromised to continue at a major-league level.
Zoom out further and the picture gets even darker. Over his last 13 MLB starts dating back to 2025, Senga is 0-7 with a 7.44 ERA and 1.80 WHIP. That's not a slump. That's a trend, and the Mets can no longer pretend otherwise.
The Velocity Story: A Telling Early Warning Sign
When Senga took the mound for his first start of the 2026 season in St. Louis, his average fastball clocked in at 97.4 mph — right where it should be for a healthy, premium starter. That number, in hindsight, was a false dawn.
As April wore on and his back worsened, manager Carlos Mendoza flagged a notable velocity drop — Senga was sitting 95-96 mph in recent outings, a seemingly minor decline that carries significant implications for how his arsenal functions. Senga's entire pitch mix is predicated on the fastball-ghost fork combination. The fork is devastating precisely because hitters are afraid of the heater. Shave off a mile or two, and the equation changes. Hitters can sit on the fork. They can foul off the fastball. The weaponization of movement depends on the velocity being credible.
Senga himself acknowledged that back discomfort had been present since spring training — he just believed he could manage it. That decision, or perhaps the pressure to contribute to a Mets team with postseason aspirations, meant the problem compounded quietly until it became impossible to hide on April 26.
A Contract Worth $75 Million and a Future Full of Questions
The business context here is impossible to ignore. Senga signed a five-year, $75 million contract with the Mets — a deal that made sense given his 2023 performance and represented a calculated risk on a pitcher who had dominated NPB for years before making the leap. But between a 2024 season lost almost entirely to a right shoulder capsule strain and a left calf strain, a 2025 season derailed by a right hamstring injury after a brilliant 7-3, 1.47 ERA start, and now a back injury in 2026, the Mets are paying elite-pitcher money for a pitcher they can almost never count on.
That calculus is now forcing difficult conversations at the executive level. Mendoza confirmed after Senga's April 26 start that he would be having conversations with team president David Stearns about Senga's role going forward. The phrasing was diplomatic but the message was clear: the current arrangement — Senga as a rotation anchor, trusted with high-leverage starts — isn't working, and the organization knows it.
What makes this particularly thorny is that Senga has leverage. His contract includes a provision that gives him the right to decline a Triple-A assignment — the kind of clause elite pitchers negotiate to protect themselves from being buried in the minors. Last September, amid the Mets' late-season collapse, Senga accepted a Syracuse assignment voluntarily. That goodwill matters. But whether he'd accept a demotion again, especially while dealing with a back injury requiring epidural treatment, is genuinely unclear.
Three Years of Injury, One Year of Dominance: Senga's Mets Tenure in Context
It's worth remembering what made Senga's signing so exciting — and what the Mets are still waiting to get back.
In 2023, he was as good as advertised. He earned an All-Star selection, finished second in NL Rookie of the Year voting, and placed seventh in NL Cy Young voting. His ghost fork — a split-finger fastball with late, diving action that falls off the table — was genuinely unhittable at times. Opponents looked lost against it. He gave the Mets the legitimate ace they'd lacked since the Jacob deGrom era.
Then the injuries came, one after another, in a sequence that would test any organization's patience:
- 2024: One regular-season appearance. Shoulder capsule strain, then a calf strain. A season effectively lost.
- Early 2025: Brilliance. Seven wins, a 1.47 ERA through 13 starts. The real Senga, back and dominant.
- Mid-2025: Right hamstring strain ends his run. The Mets' playoff hopes dim without him.
- September 2025: Senga returns to pitch in Triple-A, trying to salvage something from the year.
- 2026: Back pain from spring training, velocity down, ERA at 9.00, and now an epidural and an IL stint with no clear timeline.
The pattern is not one bad-luck injury. It's a pitcher whose body keeps finding new ways to break down, and a team that keeps waiting for the 2023 version to return. Senga himself expressed frustration at yet another setback, acknowledging the back issue had lingered since spring training before becoming unbearable during the Rockies game.
What This Means for the 2026 Mets
New York has responded to Senga's absence by reinserting David Peterson into the rotation and recalling right-hander Christian Scott, who is slated to start Friday. Both moves are sensible stopgaps, and the Mets' rotation depth is better than it would have been a few years ago. But neither Peterson nor Scott is the pitcher Senga is on his best days, and the Mets entered 2026 expecting Senga to be a genuine front-of-rotation force.
The deeper question is what happens when — or if — Senga is healthy enough to pitch again. The 7-to-10-day throwing moratorium means he won't be throwing live until mid-May at the earliest. Factor in a gradual ramp-up, a rehab stint, and the organizational caution that's warranted after everything that's happened, and a June return feels optimistic. A return to the major-league rotation in the same role he left? That's not guaranteed at all.
The Mets face a genuine strategic decision. Do they hold a rotation spot open for a pitcher who hasn't been healthy for more than a few months at a stretch since 2023? Do they send him to Triple-A to work through mechanical and health issues away from the pressure of a contending team? Or do they start exploring what a reduced, bullpen-style role might look like for a pitcher whose body may not support 180-inning seasons anymore?
None of those options are particularly attractive for a team that paid $75 million for a starter. But the Mets have always been better at roster construction when they're honest about what they have rather than what they wished they had.
Analysis: Is Senga's Career in New York Already at Its Peak?
Here's the uncomfortable truth worth saying plainly: the 2023 version of Kodai Senga may be the only version of that pitcher the Mets ever get. That's not a hot take — it's a sober reading of the evidence. He has now missed, partially or entirely, parts of three consecutive seasons with different injuries affecting different parts of his body. The back issues this year are new territory, and lumbar spine inflammation in a pitcher is particularly concerning because the rotational stress of pitching places enormous demand on the lumbar region with every single throw.
The velocity decline is the most worrying signal. Senga's fastball dropping from 97.4 to 95-96 mph while pitching through back pain isn't just a numbers story — it's a pitcher's body telling him something is wrong before his brain is ready to accept it. The ghost fork works in the context of a premium fastball. As velocity erodes, so does the deception differential that makes the fork so punishing.
This doesn't mean Senga is finished. The early stretch of 2025 — 7-3, 1.47 ERA — proved he can still be elite when healthy. But "when healthy" has become an increasingly rare condition. The Mets have to plan around that reality, not in spite of it.
"It's not good enough" — Carlos Mendoza's blunt assessment after Senga's April 26 start captures what the numbers have been saying for weeks. The Mets need answers, and right now, Senga can't provide them.
Frequently Asked Questions About Kodai Senga's Injury
How long will Kodai Senga be out?
There is currently no confirmed return timeline. Senga described his own outlook as "difficult" to predict when speaking to reporters at Citi Field on April 29. He received an epidural on April 28 and faces a 7-to-10-day period during which he cannot throw at all. Any return to pitching would require a gradual build-up and likely a minor-league rehab assignment, meaning a realistic major-league return is weeks away at minimum — and potentially longer depending on how his back responds to treatment.
What is lumbar spine inflammation and why is it serious for a pitcher?
Lumbar spine inflammation refers to irritation or swelling in the lower back's vertebrae, discs, or surrounding tissue. For any athlete, it's painful and limiting. For a pitcher specifically, it's particularly concerning because the pitching motion generates extreme rotational torque through the lumbar spine on every delivery. Senga received an epidural injection — a corticosteroid treatment delivered directly into the epidural space around the spinal cord — which is a common intervention for acute lumbar pain but is not a cure. Managing inflammation doesn't address any underlying structural issues that may have caused it.
Could Senga be sent to Triple-A instead of returning to the major-league rotation?
It's a real possibility, and one that the Mets' front office appears to be actively considering. Manager Carlos Mendoza confirmed conversations about Senga's future role will take place with president David Stearns. Senga's contract gives him the right to decline a Triple-A assignment, but he voluntarily accepted one in September 2025, which suggests some willingness to be flexible. Whether he'd accept a demotion under these circumstances remains to be seen.
What is Senga's contract situation?
Senga signed a five-year, $75 million deal with the Mets before the 2023 season. Given that he has missed significant time in 2024 and 2025 and is now injured again in 2026, the Mets are not receiving the on-field value the contract projected. That said, the contract cannot simply be voided due to injury — the Mets remain financially obligated to Senga, which adds complexity to any roster decisions they make about his role.
Is this a different injury from Senga's 2024 and 2025 problems?
Yes. In 2024, Senga missed nearly the entire season with a right shoulder capsule strain and a left calf strain. In 2025, a right hamstring strain interrupted what had been a brilliant early season. The 2026 lumbar spine inflammation is a new injury affecting a different part of his body — which, while technically unrelated to the prior issues, raises broader questions about whether Senga's body is capable of holding up under a full starting pitcher's workload at the major-league level.
The Bottom Line
Kodai Senga's story with the Mets is one of the most frustrating in recent baseball memory — not because he's failed, but because the glimpses of brilliance make the absences more painful. His 2023 season was genuinely special. His early 2025 stretch was a reminder of what he can be. But between those peaks has been an accumulation of injuries, rehab stints, and now a back problem serious enough to require an epidural and an indefinite throwing suspension.
The Mets have a decision to make, and it's more complex than simply waiting for Senga to get healthy. They need to be honest about what role this pitcher can realistically fill for the remainder of his contract — rotation anchor, depth starter, eventual bullpen option, or a roster question that's answered game-by-game depending on health. What they cannot afford is another half-season of counting on a pitcher who keeps finding new ways to get hurt.
Senga, for his part, has never shown anything but professionalism and competitive drive through everything. That matters. But drive alone doesn't keep a lumbar spine healthy, and at 32, with three injury-disrupted seasons behind him and no clear return date ahead, the window for Senga to reclaim his standing as one of the NL's elite starters is narrowing in ways that a single epidural injection cannot reverse.
