Kodai Senga, closer? Here's why it could work

Kodai Senga has the stuff -- and maybe even the moxie -- to succeed as a late-game leverage reliever for the Mets.

Did anyone have that on their bingo card?

Senga carried a 9.09 ERA and an 0-7 record into July, having allowed more earned runs (33) than innings pitched (32 2/3). But in seven games out of the bullpen this month, the embattled right-hander has a 2.45 ERA. Even after allowing a walk-off home run in Sunday's 2-1 loss to the White Sox, he has converted all four of his save opportunities. For the most part, he looks like a completely different pitcher.

What exactly is happening here? And is any of this success actually sustainable, perhaps with an eye toward 2027?

Let's start with some context. Senga is not the only rotation castoff succeeding in a bullpen role. Last week, MLB.com's Mike Petriello explored Bryan Bello's unexpected star turn, attempting to figure out how exactly Bello has turned into a lights-out reliever. Petriello started his exploration with a series of questions, the ones we typically ask when a pitcher turns his season around. Did he change his pitch mix? Is he throwing harder? Is he being more aggressive in the zone?

These same questions are applicable with Senga, and the answers are overwhelming.

We'll go in order here, beginning with Senga's six-pitch arsenal, one flush with three fastball shapes, two breaking balls and a signature forkball -- his best pitch. It's the sort of diverse repertoire that most starting pitchers have these days. Without it, it's exceedingly difficult to keep a lineup off-balance multiple times through the order, and deal with platoons.

As a one-inning reliever, though, Senga doesn't need all six pitches. He really only needs two.

“His right arm is 100 miles an hour and a nasty forkball, and that profile plays for a late-inning reliever,” interim manager Andy Green said earlier this month.

Since the Trade Deadline, Senga is throwing his four-seam fastball (64%) and forkball (25.1%) a combined 89.1% of the time.

Why does this matter? Well, Senga's other pitches haven't been very good this year -- and that's putting it kindly. In at-bats ending against Senga's sweeper, slider, sinker and cutter, the opposition is hitting .364 with a .742 slugging percentage. For comparison, Barry Bonds slugged .749 while clobbering 45 home runs in his age-38 season in 2003.

But Senga's other two pitches can be elite.

Senga's forkball is a one-of-a-kind offering, so dastardly that it has its own nickname: the "ghost fork." It is his best pitch by Stuff+, which attempts to grade how nasty a pitch is based on a model that factors in velocity, movement, location and release point. On a scale where 100 is considered average, the ghost fork has a 118 Stuff+ -- and all of Senga's other pitches rank as below average.

The ghost fork has its limitations, though. It's primarily a two-strike pitch meant to induce a wild swing outside the zone, which means that it needs to be set up by another offering. When Senga is at his best, his four-seam fastball and forkball work in tandem with one another. We've seen a lot more of that lately.

Senga's four-seamer is a volatile pitch that relies heavily on velo. That gets us to the second question from above: Is he throwing harder? In one-inning bursts, yes, Senga is letting it air out. And when Senga throws hard, his four-seamer is typically very good.

Senga's fastball success, by velocity

• 97 mph and above: .226 BA / .258 SLG / 25.4% whiff rate
• 97 mph and below: .300 BA / .720 SLG / 11.5% whiff rate

There's a gap of 216 points between the opposition's wOBA against Senga's fastball when it's 97 mph and above compared to slower than 97 mph. That's the difference between facing Yordan Alvarez and Patrick Bailey.

That's why it was so encouraging when Senga flashed elite velocity in his first two starts of the 2026 season. It's important now, too, that Senga's four-seamer is averaging 96.8 mph this month.

Senga's command is still spotty, but those numbers are skewed by Sunday's outing, when four of his seven fastballs were outside the strike zone. In his seven prior relief outings, his four-seam fastball zone rate was 53.3% -- compared to 51.6% zone rate the rest of the season.

Sunday's blip is a reminder that all of this is so new. His velo (95.4 mph) was down, too. It's not going to be perfect, especially as Senga wades into new territory, like pitching on back-to-back days for the first time in his MLB career.

But this is what the Mets have to do to decide whether there's a role for Senga on the 2027 club. At minimum, as this experiment carries on, our interest is certainly piqued.