How the Yankees turned one of baseball's worst pitchers into a dominant closer

It is September 10, 2023. The Seattle Mariners announced that RHP Luke Weaver would be designated for assignment, marking the second time this season he was DFA'd. He had signed as a free agent after the Cincinnati Reds did the same on August 16 of the same season, and every team in baseball missed the chance to claim him off waivers. After being a key piece in the Paul Goldschmidt trade and posting a 2.94 ERA in 2019, Luke Weaver posted a 5.58 ERA and 1.29 HR/9 from 2020-2022 until the Diamondbacks finally traded him at the trade deadline.

However, 2023 felt like a low point, as among the 102 pitchers who threw at least 120 innings in 2023, Luke Weaver had the worst ERA (6.40) and the third-worst HR/9 (2.11). The Yankees were able to get three solid starts out of him, which was reason enough for them to bring him back on a one-year, $2 million contract with a club option for 2025. Fast forward to the present, and the once-miserable starter is the top dog in the Yankees' bullpen, just finding his form.

Once a pitcher who could turn a struggling offense around, Luke Weaver has now taken on the challenge of playing one of the most coveted positions in baseball: closer for the New York Yankees.

Luke Weaver's rise from DFA canon to Yankees' best bullpen weapon

Last season we saw Luke Weaver play six different pitches to find anything that could help him limit damaging contact and avoid whiffs. Batters struck out at him less than 22% of the time, with a 9.8% barrel rate allowed, but Weaver seemed to have found something thanks to a new four-seam grip and a little more speed. His four-seam grip was changed after a conversation with team ace Gerrit Cole, and his technique changed as well, with the leg kick almost completely disappearing from his delivery.

The changes this made to his fastball were dramatic and helped him go from being a well-below-average hitter to one that can blow batters away and lead his arsenal.

A better fastball not only makes that one pitch perform better, but it also creates better pitch synergy with the rest of his arsenal. Opposing hitters have to fear his fastball because it generates so much momentum and is in the mid-90s, making his changeup even more devastating than it would normally be. It is truly one of the best offspeed pitches in the game, as batters have a 45.7% Whiff Rate, on the other hand, has a wOBA of .227. He has seen his changeup drop from 8.2 inches of Induced Vertical Break (IVB) to 4.6 inches, meaning it has dropped significantly more than last season.

Along with that heater getting vertical momentum, you have a combination of throws that consistently generate whiffs and chases, which has helped Luke Weaver tremendously in high-pressure situations. The equalizer is his cutter, a throw that I believe he's been tinkering with to give it some slider-like tendencies, something Aaron Boone hinted at recently. He mentioned that Weaver has been tinkering with the shape of his cutter, and we've seen him try to throw it down and away to right-handed hitters since early August:

Right-handed hitters have zero hits against his cutter with a high whiff rate, and when he establishes the outside half of the plate, the changeup becomes even more devastating. We saw this same concept against left-handed hitters when Luke Weaver painted an outside cutter to freeze Triston Casas after he threw a ton of fastballs and changeups. His cutter has become an incredible tertiary pitch for Weaver, falling between his two main pitches from a vertical and horizontal movement perspective while limiting damaging contact.

It's incredible that he made such leaps with the Yankees, especially considering how things looked for him in 2023, when he even briefly questioned whether or not his career was over:

“It just felt like I had to adapt to a lot of things, I had to muster a lot of mental strength, and that was just a real low point… At that moment, that was a point where I actually asked myself these questions like, 'Is this it?'” – Luke Weaver (via The Athletic)

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We're talking about a pitcher who was broken both on and off the field, someone who constantly changed teams and cities to find some sort of continuity between his position and his performance. Baseball is both a physical and mental game, and this may be the most fun Luke Weaver has had as a major league pitcher in years.

“I couldn't see clearly. I was unconscious most of the time. I was full of adrenaline, but it was a great time.” – Luke Weaver after his first rescue in his career

The screams from the hill and the adrenaline rush are not just a show, Luke Weaver is really is cranked up and his velocity is also increasing. Since becoming the closer and taking control of things against the Cubs, he has averaged 96.5 MPH with his fastball at a 157 stuff+ and he has strikeouts 59.3% of the batters they faced during that time period. As fall approaches, there is magic in the air as teams battle for their season every day and Weaver is firmly in the race for the division.

In what FanGraphs considers a highly game-changing situation, batters are posting batting averages of .087/.196/.087, meaning he's had 56 straight matchups in those situations without allowing an XBH. With runners in scoring position, batters posted an OPS of just .491, and as the situation became more and more tense, Weaver found ways to rise to the occasion. When that bullpen needed a hero, it was Luke Weaver who stepped in for the Yankees.

Just a year ago, Luke Weaver was arguably the worst pitcher in baseball; today he is the best reliever on the Yankees team that is hoping to go far in October.