Meet the new Luis Severino

Luis Severino turned back the clock with a vintage performance Sunday night, striking out ten batters across six flawless innings against the Cubs. He lit up the radar gun, missed bats at a high clip, and exuded energy on the mound, howling after winning a 13-pitch battle with Cody Bellinger for a key sixth-inning strikeout. 

These sort of performances were once routine for Severino, who averaged 10.5 K/9 with a 3.18 ERA across two full seasons with the Yankees from 2017-18, all before turning 25. But injuries soon mounted, and as if in a blink, that version of Severino vanished, lost in the rubble of a dreadful 2023 season. In his last year in the Bronx, the right-hander posted a 6.65 ERA in 19 games (18 starts), allowing 23 home runs in 89.1 IP. Few pitchers were hit harder. Severino’s hard-hit percentage (45%) graded out in the ninth percentile, while his Barrel% (10.4%), Exit Velocity (90.2MPH), and XSLG (.496) were all career-worsts. 

In the offseason, Severino signed a one-year, $13 million “prove it”-style contract with the Mets, who jumped the shark on a fruitful pitching market to bring Severino across town. And he has simply been tremendous, posting a 3.29 ERA through the season’s first three months, an unexpected anchor to New York’s hodgepodge rotation. 

To rediscover success, Severino did not rekindle an old version of himself. In fact, he did the opposite. Against Severino, the opposition’s swing profile — in terms of metrics like whiff rate, chase rate, and swing rate — is nearly identical to his 2023 numbers. His strikeout percentage is on pace for a career-low. He is not missing more bats, nor is he getting hitters to expand the zone. His Whiff% is merely in the 15th percentile. 

And yet, a year after being one of the hardest-hit pitchers in the majors, Severino is one of the best at inducing soft contact. His Barrel% (4.5%) is in the 87th percentile, while his hard-hit percentage has soared from the 9th percentile to the 64th. His line drive rate has plunged nearly 10% from its 2023 peak. 

Instead of inducing line drives, Severino is suddenly a ground ball machine: His ground ball rate (51.1%) is his highest since his rookie season in 2016. So not only is the contact weaker, but it is on the ground, prototypical of a batted ball less likely to do damage. 

So, how did we get here? 

The transformation is largely a byproduct of one pitch. Severino is the emblem of MLB’s sinker renaissance. 

Prior to this season, Severino had most-often thrown a sinker in 2023, doing so a measly 2% of the time. The pitch hardly registered as a part of his arsenal. In 2024, he is deploying the sinker 24.5% of the time. 

But it’s not so much how often he’s throwing the pitch as it is how successful he is with it. Among SP who have thrown at least 50 sinkers — consider that the benchmark for qualifiers — Severino’s ranks as the sixth-best, using Pitcher Run Value. He trails a group of pitchers known for touting a sinker: St. Louis’s Miles Mikolas, Houston’s Framber Valdez, Chicago’s Javier Assad, Pittsburgh’s Martin Perez, and his teammate in New York, Sean Manaea. Severino is one of just three right-handers, and he is the hardest-thrower of the group. 

The pitch has proven particularly valuable against right-handed hitters. Last year, RHB pummeled Severino, especially his four-seam fastball. The four-seamer was Severino’s primary weapon against RHB, throwing it 39% of the time. But it found virtually no success; RHB posted a .486 wOBA and .746 SLG against it. Not ideal!

But the sinker has changed everything. Already, it has supplanted the four-seamer as his go-to pitch to righties, as he throws it 33.7% of the time. It has a PVR of 8, making it the third-best sinker to RHB, behind Valdez and Manaea — two left-handers. Severino uses the sinker to pound RHB inside, holding them to a .251 wOBA and .323 SLG, in the process. 

And there is a residual effect here with the rest of the pitch mix, too. Against RHB, Severino is a four-pitch pitcher, with the sinker, four-seam fastball, slider, and sweeper. The slider and sweeper offset the sinker, tailing away from the hitter. And the four-seamer has regained its effectiveness. In using the pitch markedly less — just 24.5% of the time, a 15% decline from 2023 — Severino has rediscovered its touch. RHB have a .312 wOBA and .324 SLG against the four-seamer, a steep decline. So while the velocity of the four-seam fastball is actually down a couple of ticks (95.9 MPH compared to 96.4 MPH), the location is markedly better, and more consistent. With the sinker having success on the inside part of the plate, Severino can limit the fastball to the middle-away portion of the plate; last year, the pitch too often bled over the heart of the plate, right into the RHB’s wheelhouse. 

The story is slightly different against LHB, though it is nonetheless a successful one. Severino deploys his sinker just 15.6% of the time against lefties, and it is significantly less effective (.393 wOBA and .480 SLG). But the key here is how it alters the rest of the mix. With the sinker in tow, Severino has largely ditched the slider, throwing it just 4.5% of the time, compared to 17.8% last season — when lefties slugged .548 against it. The pitches have effectively swapped places, as Severino’s sinker largely rests in the middle of the plate, where the slider did a year ago. It’s a faster, better complement to the cutter/change combination that Severino dots against LHB, accounting for a near-.100 drop-off in SLG compared to the slider.

This is a stark change for any pitcher, but especially for Severino who, at his peak, was a dominant two-pitch pitcher. He threw his fastball-slider combo roughly 85% of the time. In 2019, just five years ago, Severino unleashed the four-seamer a whopping 56% of the time; now, it’s at a career-low 36.3%. 

But he has embraced the change, and the sinker usage is only on the rise. His three-lowest single-start sinker totals this season occurred in three of his first four starts of the year. In those outings, he threw the sinker less than 10% of the time. By contrast, three of his four starts this month feature his highest sinker usage. Against the Cubs, he peaked, throwing the sinker 30.4% of the time. 

So the sinker has effectively accomplished two goals. It has changed the batted profile against Severino, inducing more ground balls and balls hit at a softer clip, plunging his sky-high hard-hit rate. And, the sinker has taken the onus off of the four-seam fastball (to RHB) and slider (to LHB), not long ago his bread-and-butter but his bane in 2023. By PRV, those two pitches ranked as the worst pitches of his career last season. Now, thanks to the sinker, he is throwing those pitches less than he ever has. 

Amid the Mets’ sudden renaissance, Severino is in a precarious spot. He would be the most-coveted starting pitcher on the market, which is bound to favor the sellers. He would command a haul. But, to the contrary, he is the Mets bona fide ace (amid a prolonged absence to Kodai Senga) and —with his sinker at the forefront — is only trending up.