On August 10th in Atlanta, Kodai Senga recorded the first save of his professional career. Not just his MLB career, his entire career, spanning years in Japan and 3 and a half seasons in New York. He threw 18 pitches, struck out two, and didn’t allow a run. His forkball graded out at a Stuff+ of 117, 17% above the MLB average. It was one inning, but it raised a question the Mets have apparently already answered.
When interim manager Andy Green was asked about Senga’s transition to the bullpen, his response was direct: “I do think in his right arm is 100 mph and a nasty forkball, and that profile plays for a late-inning reliever.” (Anthony Dicomo, MLB.com)
Green wasn’t describing a consolation prize. He was describing a profile, and the data suggests he may be right.
Senga arrived in New York in 2023 as one of the more anticipated international signings in recent memory. He rewarded that investment immediately, posting a 2.98 ERA, 10.92 K/9, and a 3.63 FIP across 166 innings. More impressively, he got better as games went on:
| Split | IP | ERA | TBF | SO | BB | wOBA | AVG |
|---|---|---|---|---|---|---|---|
| 1st Time Through | 59.1 | 3.03 | 261 | 72 | 37 | .292 | .223 |
| 2nd Time Through | 63.1 | 3.27 | 255 | 78 | 22 | .276 | .200 |
| 3rd Time Through | 42.2 | 2.53 | 174 | 52 | 18 | .277 | .197 |
That is a signature of a true ace. Hitters couldn’t solve him no matter how many looks they got. Two injury-shortened seasons later, that pitcher has fizzled a bit. The question is whether what remains is something equally valuable, just deployed differently.
The most revealing number in Senga’s 2026 profile isn’t just his poor ERA; it’s what happens the second time hitters see him.
In 2023, Senga was genuinely harder to hit as games progressed. He was one of the few pitchers in baseball who got more dangerous the deeper into a game he went. In 2026, the opposite is true:
| Split | IP | ERA | TBF | SO | BB | wOBA | AVG |
|---|---|---|---|---|---|---|---|
| 1st Time Through as SP | 15.1 | 7.04 | 72 | 23 | 11 | .346 | .224 |
| 2nd Time Through as SP | 13.2 | 13.17 | 65 | 11 | 10 | .478 | .327 |
| 3rd Time Through as SP | 2.2 | 6.75 | 13 | 4 | 3 | .326 | .200 |
| 1st Time Through as RP | 11.2 | 3.86 | 50 | 17 | 7 | .308 | .186 |
The fastball that sat 95.7 mph in 2023 has dipped to 94.7 mph in 2025. The forkball that generated a 59.5% whiff rate in 2023 sat at 43.6% last season. The pitch that made Senga impossible to solve multiple times through a lineup was no longer impossible; it was merely average. Average is not enough when you need to navigate a lineup two to three times.
That second time through the order produced a 13.17 ERA and a .478 wOBA across 65 batters. Hitters had seen enough.
As a starter in 2026, Senga posted a 9.66 ERA and a .401 wOBA against. As a reliever, those numbers drop slightly to a 5.06 ERA and a .343 wOBA, but mainly in piggyback bullpen situations. The sample size is small, 16 innings in relief, but the direction is unmistakable. One inning at max effort, Senga is a different pitcher, with the following numbers for save opportunity in Atlanta:
| Pitch | # Thrown | Usage % | Velo (mph) | Spin (rpm) | iVB (in) | HB (in) | Whiff % |
|---|---|---|---|---|---|---|---|
| 4-Seam Fastball | 11 | 61.1% | 97.3 | 2518 | 16.1 | 6.6 | 0.0%* |
| Forkball | 4 | 22.2% | 86.2 | 1260 | -1.1 | 10.3 | 66.7%† |
| Cutter | 1 | 5.6% | 92.9 | 2643 | 8.4 | -1 | — |
| Slider | 1 | 5.6% | 87.6 | 2742 | -5 | -5.9 | — |
| Sweeper | 1 | 5.5% | 84.9 | 2558 | -7.1 | -11.9 | — |
The Mets might have a new role for Senga.
The idea of redeploying a former ace as a late-inning reliever is not new. But the outcomes vary dramatically depending on why the move is made and what the pitcher brings with him.
John Smoltz is the most famous example. After missing the 2000 season following elbow surgery, the Braves moved him to the bullpen to preserve his arm. What followed was one of the most dominant closer runs in baseball history. In 2002, he posted a 3.26 ERA with 55 saves, a National League record at the time. In 2003, he was historically untouchable with a 1.12 ERA, 45 saves, and just 8 earned runs across 64 innings. He eventually returned to the rotation and posted three consecutive sub-3.50 ERA seasons, finishing his career as the only player in MLB history with at least 200 wins and 150 saves.
The parallel to Senga is not one-to-one. Smoltz was in the league longer when he made the transition, and his stuff had not yet degraded. But the underlying logic is identical. An elite pitcher with two dominant offerings pitches in shorter bursts rather than managing attrition across a full lineup. The role did not diminish Smoltz. It extended him.
The more modern and more directly comparable example is Luke Weaver. Drafted in the first round by the Cardinals in 2014, Weaver spent the better part of a decade trying to stick in a rotation. He never did stick in the rotation. Over 106 career starts, he posted a 4.57 ERA, bouncing between organizations and posting a 6.40 ERA across 123.2 innings in 2023 alone. He was throwing seven different pitches, none of them elite enough to carry a start.
The bullpen changed everything. Weaver simplified to three pitchers:
50% fastball (95.3 mph, 19.1 inches of iVB and 6.4 inches of tail)
35% changeup (88 mph, 5.4 inches of iVB and 13.1 inches of tail)
15% cutter (90.5 mph, 10 inches of iVB and 2.7 inches of cut)
The results were immediate. In 2024, he posted a 2.89 ERA across 62 appearances. In 2025, it was 3.62. In 2026, he owns a 1.80 ERA, a 2.98 xERA, and a 29.9% whiff rate. His changeup, once just another pitch in his crowded arsenal, now grades at the 94th percentile in run value.
Weaver was never an ace, but his transformation illustrates exactly what the Mets are hoping with Senga. A pitcher simplified to his best offerings and deployed correctly can become something entirely different.
Lastly, Jeff Hoffman proves the same point from a different angle. A first-round pick who spent years failing to develop enough to start, Hoffman moved to the bullpen and became one of the most effective relievers in baseball. In 2026, he owns a 37.3% whiff rate at the 99th percentile, a 34.6% K rate at the 98th percentile, and a 3.57 xERA. Three pitches, max effort, one inning.
The patterns across all three are consistent. Simplification plus role fit plus elite stuff equals a different pitcher entirely. The Mets are testing if Senga fits that pattern. The early data suggests they may be right.
The version of Senga that the Mets are building toward is not the one that arrived in Queens in 2023. That pitcher no longer exists. Injuries and league adjustments have seen to that. What remains is something different: a 33-year-old with an upper-90s fastball and one of the most disorienting forkballs in baseball, no longer asked to solve the same lineup three times but instead deployed to end games.
The stuff is still there. In his August 10th relief appearance, Senga’s four-seam averaged 97.3 mph, touching 99 mph, and the forkball still grades out to elite. When he does not have to pace himself across six innings, the two pitches Andy Green described are exactly what they were always supposed to be: a triple-digit fastball and a forkball that hitters cannot catch up to.
The numbers support the direction. The contact profile has also improved; opponents’ wOBA has dropped 58 points from his starter line. Small samples, but consistent with what Smoltz, Weaver, and Hoffman all demonstrated. Ultimately, the bullpen does not just change a pitcher’s role; it can change what the pitcher actually is.
What remains unknown is whether Senga can sustain it. Sixteen innings is not a body of work. High-leverage late-inning appearances against top-of-the-order hitters are a different challenge than piggyback spots against a lineup. The walk rate, which ballooned to 18.8% as a starter in 2026, will need to come down from the role to work consistently. And the forkball, while still elite in short bursts, has not yet returned to the 59.5% whiff rate that made him one of the most untouchable pitchers in baseball three years ago.
But the Mets are not asking Senga to be that guy again. They are asking him to be something more sustainable. Two to three pitches, max effort, one inning at a time. The framework exists. The comps are encouraging. The stuff, when unleashed without the burden of a full start, still plays at an elite level.
Whether Kodai Senga becomes one of the game’s elite late-inning arms or whether the transition reveals new limitations is the most interesting remaining question of his 2026 season. For one night in Atlanta, at least, the answer looked exactly like what Andy Green described.
