Devin Williams & Luke Weaver Are Transforming Mets' Bullpen

Devin Williams slapped Mark Vientos on the shoulder and roared toward the Mets dugout last Sunday at Citi Field while the crowd showered him with applause. Austin Wells had grounded into a double play. Vientos’ lightning-quick play at first base to start the classic “3-6-3” double play with shortstop Bo Bichette ended the Yankees’ rally and left them scoreless in the top of the tenth inning.

The revamped Williams once again exceeded expectations. He did it by retiring all three hitters he faced to earn his sixth save of the season — his fourth consecutive hitless appearance. Then, after Tyrone Taylor’s dramatic game-tying homer in the bottom of the ninth on Sunday made it 6-6, Williams delivered again in the biggest moment, giving the Mets a chance to win the Subway Series at home. And they did. Carson Benge hit a walk-off grounder, and the Mets defeated the Yankees 7-6 in the series finale.

The Yankees have not won the Subway Series since sweeping the Mets in 2017. Every pitch carries pressure, every inning feels heavier, especially after the Mets’ rocky start in April.

For much of April, the Mets bullpen created a strange feeling: too much talent to look this vulnerable. It was not a velocity issue. It was not a lack of stuff. It was something harder to identify at first glance — and far more dangerous for a contender. Their top relievers had lost the ability to control how hitters reacted against them.

Swings no longer looked uncomfortable. At-bats stopped feeling rushed. Opposing lineups entered the late innings believing they could survive them.

And in modern baseball, especially for teams built to compete in October, that changes everything. A dominant bullpen shortens games. It allows managers to aggressively navigate the first six innings knowing the game can effectively end in the seventh.

That is exactly what the Mets stopped having for several weeks.

Devin Williams looked like a pitcher trapped between two versions of himself. Luke Weaver, whose recent reinvention had quietly become one of the most fascinating stories among relievers, began losing the depth and precision that allowed him to avoid damage. The result came quickly: too many extended innings, too much hard contact, and too many situations where every lead started feeling fragile.

But May has looked completely different. And the numbers help explain why.

Improvements From Devin Williams and Luke Weaver

The statistical differences are dramatic enough to feel almost unreal. Williams went from allowing eight runs in four innings to stringing together double-digit nearly flawless appearances. Weaver went from a stretch where hitters were barreling baseballs consistently to a scoreless run while nearly doubling his ability to generate swings and misses.

A large part of the Mets’ collapse in April felt inevitable whenever Williams and Weaver struggled. The results are there. Williams’ rough outings were part of a 3-3 stretch for the club in the six appearances before his current streak of nine nearly perfect relief outings.

Weaver’s struggles came within an even more chaotic stretch, with the Mets going 1-6. And it makes sense: Weaver pitches before Williams. If he falters, Williams often never becomes an option because the scoreboard changes and the Mets’ chances of winning disappear before the ninth inning arrives.

But the most important development is not simply the reduction in damage. It is the way both pitchers regained control of at-bats.

When Williams struggled, his innings felt long. Hitters no longer looked uncomfortable working from behind in counts. The changeup still moved, but something fundamental had disappeared: the visual effect of his entire arsenal. His famous changeup has always been devastating, but it never worked in isolation. The pitch survives because of the threat of the fastball.

That is exactly what the newest data shows.

How They Are Reclaiming Their Dominance

The table explains something essential about Williams: his dominance returned once he reestablished vertical aggression with the fastball. During April, too many fastballs drifted into neutral zones, particularly at heights where hitters could stay balanced and recognize the changeup early. The result was devastating for a pitcher whose effectiveness depends on sequential deception.

The new whiff chart against the four-seam fastball reveals a completely different reality. Williams has returned to attacking above the strike zone, especially in the upper inside quadrants, where swing-and-miss rates have exploded. Entire zones are now producing extreme whiff percentages, completely changing the dynamic of the at-bat.

That happens because the fastball does not necessarily need to generate weak contact to dominate. Its effect comes from accelerating decisions. When the fastball explodes at the top of the zone with vertical life, hitters feel forced to begin their swing earlier. And that is where Williams’ real trick appears: the changeup comes out of the exact same visual tunnel before disappearing beneath the bat too late for hitters to adjust.

Williams had allowed an astonishing .857 BABIP during the previous six-game stretch. His weapons were completely disconnected. Now, opponents have dropped to a .071 BABIP against him. It is not only that he is striking hitters out and generating elite swing-and-miss rates with the fastball. He is also eliminating damaging contact. That is why both pitches are functioning so aggressively at the same time. The fastball owns a 52.9% whiff rate. The changeup sits at 47.6%. Neither pitch has allowed a barrel. Hitters are making the wrong decisions from the very beginning of the at-bat.

That difference may look subtle from the outside, but it completely transforms the offensive experience against a reliever. In April, hitters looked like they were waiting for mistakes. Now they look reactive.

Weaver found his adjustment from a different place, but one equally important. His problem was never the total absence of swings and misses. The issue emerged when he lost the ability to control the type of contact he allowed. Too many changeups stayed over the plate or entered trajectories where hitters could fully extend their arms.

The exit velocity chart against the changeup clearly shows how he corrected that. The weakest contact consistently appears below the strike zone, especially on the lower outer edge, where exit velocities collapse to minimal levels. There are balls coming off the bat at 75 and 77 mph — essentially dead contact from the moment of impact.

That reflects exactly who Weaver needs to be in order to dominate.

Unlike Williams, Weaver does not survive by destroying timing. He survives by manipulating the contact plane. Even during his worst stretch, his ground-ball profile remained alive, producing a 50% ground-ball rate. When the changeup finishes low, it forces hitters to either pound the top half of the baseball or swing over it entirely. The damage disappears because the swing never finds the correct angle.

And the chart also reveals where the problem existed during his rough stretch. The only area where the changeup was truly punished came on pitches located low and inside, where exit velocities climbed above 90 mph. That small location mistake was enough to completely alter his innings.

Now he is avoiding that zone entirely. And that explains why the Mets are beginning to recover something far more important than attractive statistics: they are recovering the feeling of control at the end of games.

With the Williams-Weaver duo dominating, the Mets bullpen has improved to a 2.44 ERA during the month of May. Now the problems lie elsewhere. Without the blowups from Tobias Myers and Craig Kimbrel, that bullpen ERA drops all the way to 1.30.

And that is the key here: Williams has restored fear from the top of the strike zone. Weaver has returned to eliminating damage from the bottom. Together, they are rebuilding the emotional structure every bullpen needs if it hopes to get to and survive October.