You'd think the most dominant closer in the 2024 playoffs -- or at the very least, the most dominant closer in the ALCS -- would be Emmanuel Clase. But really, it's been Luke Weaver.

The Yankees closer, who was not a closer at all until September, and who was a journeyman starter until this year, has saved all four of his postseason opportunities without blemish, and has finished off all five of the Yankees' wins. Three of Weaver's four saves have been longer than one inning. He has nine strikeouts, and just three hits allowed, in his seven innings. And he just allowed his first run of the playoffs -- a solo homer to the other team's best hitter (José Ramírez) in a four-run game.

Here's how Weaver changed his identity as a pitcher to go on this run.

When Weaver took over the ninth inning down the stretch, MLB.com Yankees reporter Bryan Hoch detailed how Weaver had refined his arsenal to become a force out of the bullpen. Most importantly, Weaver tweaked his four-seam fastball release to generate more rising movement, while also tweaking his changeup release to add more depth. (Pitching analyst Lance Brozdowski also did an excellent breakdown of Weaver's adjustments this week.)

Let's take a closer look. We want to show you exactly what Weaver's new stuff looks like. Because in the postseason, Weaver has taken it to another level.

The difference between Weaver's four-seam/changeup combo from 2023 to 2024 is stark. Weaver might as well be a different pitcher.

Here's the movement profile of Weaver's arsenal last season compared to this season. The four-seam fastball is in red, and the changeup is in green. (The size of the circles is proportional to his usage of each pitch type). Look how the four-seamer shifts up from 2023 to 2024, and the changeup shifts down.

That's the change in Weaver's induced vertical break -- the amount of break he generates from how he spins the ball, taking out the amount a pitch will naturally drop along its trajectory due to gravity.

In other words, the movement chart is showing the extra rise Weaver is generating on his fastball, the extra drop he's generating on his changeup -- and, most importantly, the much greater difference in movement between his two key pitches. That movement differential, that new and improved relationship between the four-seamer and changeup, is what makes Weaver so good right now.

We can break down how Weaver changed each pitch to create one of the elite fastball/changeup combos in baseball.

THE 4-SEAMER

Last season, when Weaver spent most of the year as a starter with an ERA over six, his fastball was basically an average big league fastball. His fastball averaged 94 mph, with vertical and horizontal movement that were right at the MLB average for a right-handed pitcher.

But he entered this season with a truer four-seam grip, courtesy of the Yankees, and his fastball took off -- literally. Weaver has added almost two mph of velocity and almost three inches of rise to his four-seamer, going from a mundane fastball to one of the top rising fastballs in the Majors.

Weaver's 4-seamer, 2023 vs. 2024

• 2023: 94.0 mph / 16.0" induced rise
• 2024: 95.7 mph (+1.7 mph) / 18.6" induced rise (+2.6" of rise)

As the season has gone on -- and specifically since he took over the closer's role in the Bronx -- Weaver's fastball is getting more and more explosive. Weaver has one of the top rising fastballs among right-handed pitchers since the start of September.

He averaged 19.3 inches of induced rise in September, his most of any month during the regular season. And he's now inducing 19.6 inches of rise in the playoffs.

Rising movement is generally what makes a fastball a swing-and-miss fastball, because hitters will whiff underneath the baseball. When you add Weaver's rise to his mid-to-upper 90s velocity, you get one of the toughest heaters to hit in the playoffs.

Top rising fastballs among pitchers with 95+ mph velocity
2024 postseason (min. 25 4-seamers thrown)

• Luke Weaver (NYY): 95.9 mph / +19.6 inches induced rise
• Beau Brieske (DET): 96.8 mph / +19.6 inches induced rise
• Jeremiah Estrada (SD): 98.0 mph / +19.4 inches induced rise
• Cole Ragans (KC): 95.3 mph / +19.2 inches induced rise
• Andrew Walters (CLE): 96.5 mph / +18.7 inches induced rise

The ride on Weaver's four-seamer means he can overpower hitters with fastballs upstairs -- he's done that several times already this postseason, with elevated fastball K's of Michael Massey in Game 1 of the ALDS, Salvador Perez in Game 4 of the ALDS and Daniel Schneemann in Game 1 of the ALCS. Here's what Weaver's high heat looks like from the hitter's point of view, using Statcast's 3D tracking technology.

Weaver has credited Yankees ace Gerrit Cole with helping him figure out how to throw his new version of the four-seamer -- Cole, of course, being a prototypical power pitcher with one of the best rising fastballs in the Majors. And you can see the hallmarks of Cole's four-seamer in Weaver's.

Cole's 4-seamer vs. Weaver's 4-seamer in 2024
Regular and postseason combined

• Weaver: 95.7 mph / 2,466 rpm / 19" induced rise / 6" arm-side run
• Cole: 96.0 mph / 2,364 rpm / 18" induced rise / 7" arm-side run

Weaver's fastball has a very similar profile to Cole's -- the velocity, the high spin and the movement, rise and run, that results from that spin. Their fastballs even come out of their hands with the same spin direction, which is near-true backspin, allowing both of them to achieve that explosive rising movement.

Those are two swinging strikes on elevated, rising fastballs from Weaver and Cole against the Royals this postseason. Same style.

THE CHANGEUP

Meanwhile, Weaver has taken his changeup movement in the opposite direction. He is getting much more drop on his changeup in 2024 than he was in 2023.

Due to the new way he releases his changeup, Weaver is inducing 3.6 more inches of drop in 2024 than he was in 2023. His changeup has gone from having well below-average depth, to having slightly above-average depth.

Similar to his fastball, the way he's achieved his new movement on his changeup is by changing the way he orients the seams of the baseball when he throws the pitch.

The way the seams are facing when you release a pitch can change the trajectory of the baseball through the air, and produce both more movement and unexpected movement for the hitter -- a phenomenon known as "seam-shifted wake," which MLB pitchers are increasingly pursuing. Weaver has harnessed this effect -- as he explained to The Athletic's Eno Sarris the other day -- to make his changeup much nastier.

Consider this: Weaver is throwing his changeup a lot harder in 2024 than he was in 2023 -- his average velo has increased by 2.6 mph -- which would normally mean the pitch would lose vertical movement, because it has less time to drop from Weaver's hand to the plate. But instead, Weaver's changeup has added downward vertical movement.

Weaver's changeup, 2023 vs. 2024

• 86.1 mph / 28.8" total downward movement (including gravity)
• 88.7 mph / 29.9" total downward movement (including gravity)

That is no accident. It's Weaver's new seam-shifted wake changeup in action.

Weaver's changeup now comes in at close to 90 mph, but then dives down below the zone. That gets some pretty ugly swings from hitters -- like on Weaver's strikeouts of the Guardians' Will Brennan and Josh Naylor in Game 1 of the ALCS. Here's how those changeups moved, from the hitter point of view.

THE 4-SEAM / CHANGEUP COMBO

Now let's put the two pitches together. Weaver's fastball and changeup are each individually much better pitches than they were before. Their stuff grades are the best they've ever been. But the reason Weaver has been so great as the Yankees' closer is because of how they work together.

Let's go back to Weaver's pitch movement charts for 2023 vs. 2024. The key thing to notice is how much bigger the movement differential is between his four-seamer and changeup in 2024, all while maintaining a similar velocity differential between the two pitches.

The extra separation between Weaver's four-seam and changeup break is what really makes the difference. Especially when you consider Weaver's deception on top of that.

That's the extra layer Weaver's new pitch grips have created. Weaver's four-seamer and changeup look very similar out of his hand, but by the time they reach the hitter, they're moving much differently.

That's not what was happening in 2023. You can see that here, comparing the movement direction of Weaver's pitches at pitch release to their movement direction when they get to the plate. This year, the divergence in movement between Weaver's fastball and changeup in flight is much, much more.

The four-seamer stays true and carries through the zone -- that's Weaver's new rising fastball grip at work. And the changeup fades much more than you'd expect from the way it comes out of Weaver's hand -- that's his new seam-shifted wake changeup grip.

In concert, that two-pitch combo has become nearly unhittable. It's all Weaver needs.

Weaver's four-seamer and changeup have gotten so good that it's allowed him to simplify his pitch arsenal. He'd already scrapped his old breaking balls, a knuckle-curve, slider and sweeper, from last year to this year in favor of a three-pitch mix: fastball, changeup, cutter. But in the postseason, he's gone one step further: Weaver has essentially scrapped the cutter, too.

Let's take a look at two beautiful fastball/changeup combos Weaver has pulled off these playoffs: One elevated four-seamer/low changeup pairing to strike out Perez, another to strike out Massey. Here are those pitches overlaid for each hitter, both on video and with Statcast 3D tracking. The movement takes the fastball and changeup so far apart from Weaver's release point to the plate, and the hitters have no chance to cover both pitches.

Postseason Weaver is a fastball-changeup relief ace. And with the new versions of those two pitches at his disposal, no one's been able to beat him yet.