Devin Williams’ Changeup Is Not As Effective As It Once Was, Resulting in Unfamiliar Numbers

After the Mets lost closer Edwin Diaz to the Los Angeles Dodgers over the offseason, they made a splash and signed Devin Williams to take his place. He’s under contract for three seasons, but hasn’t gotten off to a great start.

Williams earned the honors of National League Rookie of the Year back in 2020 and was made two All-Star rosters while with the Milwaukee Brewers. The Brewers are heavily driven by analytics and are considered to be one of the best teams year in and out with roster construction, especially when it comes to pitching. Ever since getting shipped out of Milwaukee, Williams hasn't been the same.

Part of this could be as a result of him dealing with a back stress fracture during the 2024 season that limited him to just 22 games. In December that year, the Brewers sent him to the New York Yankees in a deal that would bring back Caleb Durbin and Nestor Cortes.

The profile on Williams is simple: He doesn't have elite velocity, but will miss bats with his stuff and limit hard contact. His nasty changeup allowed him to fetch excellent ground ball rates during his best years.

While he has maintained his ability to strike out a surplus of batters, his ability to get batters to hit the ball on the ground has seen a decline with the Mets this year.

Why Is Devin Williams Generating Fewer Groundballs with the Mets?

Williams’ changeup constantly has graded out to be well above average according to Stuff+. From 2020-2025, his changeup has graded as high as 140 and as low as 114 according to FanGraphs Stuff+. This year, it’s taken a significant and concerning dive down to 82.

Diving into the traits of his changeup, it lost a noticeable amount of vertical drop this year. That offering had an incredible 44.3 inches of vertical drop last year which is his career best, but has sat between 40 and 42 inches throughout his career.

So far in 2026 with the Mets, his changeup is only averaging 38.9 inches of vertical drop. That has led to Williams having the lowest groundball percentage of his career; his groundball rate has averaged 46.9%, but he's down to 37.9% in 2026.

This is reflected very clearly if you look at Williams’ run value on off-speed pitches, which only accounts for his changeup. It currently has a run value of -2 (8th percentile), but it’s been as high as 15 during the 2023 season.

Batters are whiffing less against it and it has not been as effective at putting opponents away. Williams’ changeup has drawn a 40.4 swing-and-miss rate which is down from where it’s sat between 43% and 48% in the past. That figure is still pretty elite, but margins like these are the difference between an All-Star closer and a middling reliever.

Will Devin Williams Return to Elite Form?

For a guy who’s relied heavily on his changeup for success, it’s definitely concerning to see decline in the effectiveness of his best pitch. During his best years, he went to his changeup between 57-63% of offerings. This year is the first time in Williams’ career that he’s used his four-seamer more than his changeup.

Williams hasn’t seen great results when batters put his changeup in play. Opponents are hitting .357 against the pitch with a .424 xSLG and .410 xOBA. While the expected batting average against his changeup is lower at .257, batters are still crushing the pitch with a .500 slugging percentage.

He’s been a tad unlucky thus far through 11 innings of work. While his 6.55 ERA doesn’t look good, Williams has a 3.49 xERA and a 2.69 FIP. Seeing his FIP under three is what’s encouraging with Williams. He owns a career 2.46 mark in that category because of his high strikeout rate while not allowing many home runs.

It might be the Mets wanting him to use his fastball more, or maybe he’s just not confident with his changeup right now. There is still plenty of time left in the year for Williams to figure things out, but it’ll be important to monitor how effective his "airbender" will be going forward.