How Yankees closer Luke Weaver went from journeyman starter to dominant reliever

NEW YORK -- It's a bad postseason to be a great closer. Devin Williams served up Pete Alonso's series-winning three-run homer in Game 3 of the Wild Card Series. Carlos Estévez gave up Francisco Lindor's series-winning grand slam in Game 4 of the NLDS. Emmanuel Clase allowed five earned runs during the regular season, then coughed up three on one Kerry Carpenter swing in the ALDS. Edwin Díaz continues struggling with his slider . Even the best closers are faltering this October.

And then there's Luke Weaver , the unassuming right-hander who had a 6.40 ERA with three teams as a starting pitcher in 2023, and is now a perfect 4 for 4 in save chances for the New York Yankees this October. He recorded at least four outs in three of those saves. Weaver has not allowed a run this postseason and he's retired 18 of 21 batters faced, and he nailed down the final five outs in New York's ALCS Game 1 win over the Cleveland Guardians on Monday .

Weaver finished last season with the Yankees, making three meaningless starts (meaningless because the Yankees were out of the postseason race) in September after coming over on a waiver claim. The two sides built a relationship, and the Yankees brought Weaver back on a one-year, $2 million free-agent contract essentially to be a depth starter. Instead, he's emerged as a bullpen force, and that contract includes a bargain $2.5 million club option for 2025.

"Really since the end of spring training, his last couple outings in spring training, he really started to look the part," Yankees manager Aaron Boone said about Weaver's emergence on Monday. "I remember going into Houston, that opening series, and he is kind of our long man, maybe a sixth starter at some point. We're not really sure of the role. Really from jump, it's been excellent."

There were reasons to think the Yankees made a smart move re-signing Weaver over the winter , but if you gave the Yankees a truth serum, even they'd likely tell you they didn't expect him to be this good. Weaver pitched to a 2.89 ERA and struck out 103 in 84 2/3 innings during the regular season, and ranked ninth among all relievers in win probability added. Now he's arguably the best closer remaining in the postseason given how many hiccups other top end-game relievers have had.

Here are three reasons Weaver went from journeyman back-end starter to shutdown closer for the Yankees.

1. He revamped his delivery

Pitchers show up to spring training with a new pitch or a new grip all the time. Every spring, like clockwork, we hear those stories, and many times those new pitches get put on the shelf during the regular season. It's not often a pitcher shows up to camp with a reworked delivery, though. When Weaver reported this spring, he brought with him a revamped delivery with little to no leg kick.

Here is Weaver with his new and old deliveries:

"Feeling like there was less thinking mechanically and more just about pitching," Weaver said about his new delivery in March ( via the New York Post ), adding he just kind of stumbled into it over the winter and didn't set out specifically to make these changes.

During the regular season, Weaver said his new delivery allowed him to better use his athleticism, and he felt it also improved his recovery between outings.

He feels less wear and tear. It's also pretty deceptive, no? Hitters are used to some kind of leg kick, but Weaver gets right into the pitch and jumps on the hitter. The new delivery helped bring out a new version of Weaver.

"I think with some of the tweaks he made to his delivery over the winter that didn't show up, frankly, right away in spring training has really taken him to another level," Boone said Monday.

2. His velocity jumped in the bullpen

It is not uncommon for pitchers to see their velocity tick up in the bullpen. As a starter, they have to pace themselves a bit to get through five innings and two turns through the lineup (or more). In a short relief role, even as a four-to-six out guy, they can air it out and put the pedal to the floor right out of the gate. Weaver's fastball velocity is the best of his career this season.

A graph is worth a thousand words:

As a starter, Weaver sat 94 mph and would occasionally scrape 97 mph. As a reliever this year he's sitting close to 96 mph and has flirted with 99 mph on a few occasions. A year ago, hitters missed with 17.5% of their swings against Weaver's fastball, below the 21.8% league average on heaters. Thanks to that added velocity, Weaver's fastball whiff rate is up to 30.0% in 2024.

"He's got command, the uptick in stuff that we've seen in him as a reliever," Boone said Monday when asked what has made Weaver so successful as a reliever.

3. The Yankees tweaked his changeup

Dating back to Sept. 1, Weaver has struck out 34 of 66 (51.5%) batters faced. Fifteen of those 34 strikeouts have come on his changeup, a pitch that had a 48.0% whiff rate during the regular season. The MLB average whiff rate on changeups is 30.8%, and among the 76 pitchers who threw at least 300 changeups in 2024, only teammate Carlos Rodón had a higher whiff rate (49.0%).

The changeup has been Weaver's go-to secondary pitch throughout his career, though it was always more of an average offering than a knockout putaway pitch. This year the Yankees helped Weaver tweak his changeup grip, and that adjustment turned it into one of the best in the sport. Here are the nerdy details (I mean that as a compliment):

Weaver's changeup whiff rate jumped from 32.3% last year to 48.0% this year. And when hitters did get the bat on his changeup, they had a .173 average and .263 slugging percentage. The average exit velocity allowed on the pitch was a mere 83.9 mph. It's hard to make contact with Weaver's changeup in general, and it's almost impossible to square up.

Weaver has never lacked talent or pedigree. He was the No. 27 pick in the 2014 draft and the headliner in the trade package that sent Paul Goldschmidt to the St. Louis Cardinals . He's also had some injuries. For a long time, Weaver was a talented pitcher struggling to put it together. Now, at age 31, he's found a home in the bullpen, and in the ninth inning for the Yankees.

"He's a better pitcher than he's probably ever been in his life," Boone said during New York's Wild Card Series off week. "And that's a credit to him for some of the adjustments he's made and how he's embraced going to the bullpen. He's had an outstanding season."