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

It’s September 10, 2023. The Seattle Mariners have announced that RHP Lucas Wever would be designated for assignment, marking the second time he had been DFA’d that season. He had signed as a free agent after the Cincinnati Reds did the same on August 16 of that same season, and every team in baseball passed up an opportunity to claim him off waivers. After playing a key role 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, with the Diamondbacks ultimately letting him go at the trade deadline.

2023 felt like a low point, though, as of the 102 pitchers who threw at least 120 innings in 2023, Luke Weaver had the worst ERA (6.40) and third-worst HR/9 (2.11). The Yankees would get three solid starts out of him, which gave them reason to bring him back on a one-year, $2 million deal with a club option for 2025. Fast forward to now, and the once-abysmal starter is the odds-on favorite in a Yankees bullpen that has been finding form.

Luke Weaver, once a pitcher who could turn a slumping offense around, has taken on the challenge of filling one of the most coveted roles in baseball; closer for the New York Yankees.

Luke Weaver’s rise from DFA fodder to the Yankees’ best bullpen weapon

Last season we saw Luke Weaver use six different fields in an attempt to something that could help him limit damaging contact and pick up mishits. Batters were missing less than 22% of the time against him with a 9.8% barrel rate, but Weaver seemed to be finding something thanks to a new four-seam grip and some more speed. His four-seam grip was adjusted after a conversation with team owner Gerrit Cole, and his mechanics changed as well, with the leg kick he had all but erased from his throw.

The changes he made to his fastball were dramatic, transforming it from an underwhelming offering to one that stuns hitters and is a focal point in 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. Opponents should fear his fastball because it generates so much drive and sits in the mid-90s, making his changeup even more devastating than it normally would be. It’s truly one of the best offspeed pitches in the game, as batters have a 45.7% Whiff Rates Against with a .227 wOBA. He’s seen his changeup go from 8.2 inches of Induced Vertical Break (IVB) to 4.6, which is down significantly more than last season.

Combined with that heater that got vertical ride, you have a combination of pitches that consistently generate whiffs and chases, something that has helped Luke Weaver immensely in high-leverage situations. The equalizer is his cutter, a pitch that I believe he’s been tinkering with to give him some slider-like tendencies, as Aaron Boone recently hinted at. He said Weaver was tinkering with the shape of his cutter, and we’ve seen him try to throw it to right-handed batters since early August:

Righties have zero hits against his high whiff rate cutter, and by establishing the outside half of the plate the changeup becomes even more devastating. We’ve seen this same concept against lefties, with Luke Weaver painting an outside cutter to freeze Triston Casas after he’s thrown a series of fastballs and changeups. His cutter has become an incredible tertiary pitch for Weaver, sitting between his two primary pitches from a vertical and horizontal movement standpoint while limiting damage contact.

It’s incredible to think that he’s made such huge strides with the Yankees, especially considering how things looked for him in 2023, when he briefly wondered whether or not his career was over:

“It just felt like there was a lot of adjustment that had to be made, a lot of mental strength that I was trying to overcome and that just felt like a really low point… At that point, that was a point where I was asking myself those 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 was constantly moving between teams and cities as he tried to find some kind of continuity with where he was and how he was performing. Baseball is as much a physical sport as it is a mental one, and this might be the most fun Luke Weaver has had pitching at the Major League level in years.

“I couldn’t see straight. I was unconscious most of the time. I was on pure adrenaline, but it was an amazing time.” – Luke Weaver after his first career save

The screams from the hill and the adrenaline rush aren’t just for show, Luke Weaver is Real and his velocity is also on the rise. Since becoming the closer and closing it out against the Cubs, he’s averaging 96.5 MPH on his fastball with a 157 Stuff+, and he’s 59.3% of the batters faced during that span. There’s magic in the air when fall arrives, as teams fight for their season every day, and Weaver is firmly in the mix for a division chase.

In what FanGraphs considers a high-leverage situation, batters are hitting .087/.196/.087, meaning he’s had 56 consecutive matchups in those situations without allowing an XBH. With runners in scoring position, batters have posted an OPS of just .491, so as the heat heats up, Weaver has found ways to rise to the occasion. When this bullpen needed a hero, it was Luke Weaver who stepped up for the Yankees.

Just a year ago, Luke Weaver was arguably the worst pitcher in baseball; now he’s the best reliever on a Yankees team looking to put together a winning streak in October.