Paul Skenes, in the midst of one of the most impressive rookie pitching seasons in decades, releases his 99 mph four-seam fastball from 5.7 feet high, just a tick under the Major League average of 5.8 feet. Jeremiah Estrada, a breakout San Diego reliever who struck out 13 consecutive hitters earlier this season, has a fastball with similar characteristics – 97 mph and released from 5.9 feet, so only just a touch higher and a touch slower.

They’re both having excellent seasons, yet their fastballs behave considerably differently. Estrada has truly elite rising action on his heater, getting that strong backspin that’s become so popular around the game over the last decade. It causes batters to consistently swing under the ball, and indeed he has a 33% swing-and-miss rate.

Skenes, however, does not; his four-seamer gets below-average rise and has a little horizontal cut to it, which led to some mild pre-Draft concerns over whether his fastball shape would be more hittable than the velocity would imply. That has hardly been an issue, of course, and it's still a good pitch. It's not his best pitch, though, and a 24% swing-and-miss rate is certainly less than Estrada's.

They’re both fastballs, they’re both thrown hard, they’re both released from the same vertical spot, they even have indistinguishably different spin rates. But despite all that, they don’t behave similarly at all. Skenes’ fastball drops twice as much on the way to the plate as Estrada’s, and it has more than an extra foot of arm-side movement as Estrada’s relatively vertical offering.

That doesn’t happen by accident. So what’s the difference? It’s how they stand, how they release the ball, and how differently you can release otherwise similar fastballs from otherwise similar spots off the ground.

Skenes is 6-foot-6, making him one of the sport’s taller regular starters. Estrada, meanwhile, is listed as 6-foot-1, which is more middle of the pack. The five-inch difference in height gets exacerbated by how tall (or not) they stand when they get down the mound, where Estrada gets further out front despite his shorter frame – his extension off the rubber is 6.8 feet, higher than Skenes’ 6.4 – and so, stretched out more than his taller Pittsburgh counterpart, Estrada’s shoulder is a full foot lower (3.6 feet) than Skenes’ (4.6 feet).

And yet, they get the same release height, which is only possible because Estrada keeps his arm as vertical as possible, and Skenes does not. Estrada, per Statcast’s newly released arm angle metrics (now available at Baseball Savant), has the second-highest arm slot of any regular pitcher, at 65° (where 90° would be straight up, and 0° would be sidearm). Skenes, at 24°, is lower than average – not quite sidearm, but into the low three-quarters range.

That helps give these otherwise similar fastballs different spin directions (12:15 p.m. on a clock face for Estrada, or near-perfect backspin, as compared to 2:00 p.m. for Skenes, which helps create that run). The combination of height, extension, and release point – some of the building blocks of vertical approach angle, or the angle that the pitch reaches the plate, which can be a powerful tool of deception – explains why these two fastballs act so, so differently.

There is, as always, more than one way to find success on the mound, whether that’s via added velocity, new pitch types, or simply changing up the look you’re offering to hitters. Lest you think that release points and arm angles aren’t included in that, allow us to remind you of the dizzying array of looks the 2020 Rays pitchers threw at their opposition on the way to an American League pennant.

Most pitchers are relatively consistent here, with approximately 75% staying within 3° from year-to-year, and it’s easy to find a reliable veteran like Jameson Taillon just doing the same thing, over and over.

But it’s also easy to find examples of arm slot changes helping to lead to success.

"Maybe 45 seconds into the call,” Giants ace Logan Webb told the Score in 2022, relaying his introductory meeting with then-Giants director of pitching Brian Bannister back in the 2019-’20 offseason, “he’s talking about how I'm going to change arm slots."

The instruction was to drop down and try to throw similarly to Chris Sale, the better to help Webb move away from the high four-seam approach that didn’t work for him and get the most out of the east/west sinker/slider game that did.

It’s true that the average release point has gotten lower over the years, down to a tracking-era low 5.8 feet this year. But that’s not necessarily new – we know that long-ago legends like Don Drysdale and Walter Johnson were hardly all over-the-top, for example – and it's really more about each pitcher finding what works best for them.

So: Can we use this data to find some interesting examples of players who have changed their arm slot in the last year or two and then thrived? We sure can, and below are six who stand out. (We can also find examples of pitchers who did this and didn’t find success, like Chad Kuhl, who dropped his angle more than anyone and posted a 5.06 ERA for the White Sox. It’s never one-size-fits-all; it’s not “everyone should do this.”)

Speaking of pitchers trying to imitate Sale …

LHP Sean Manaea, Mets

Ironically for the Braves, who are in a day-by-day (and, at the moment, head-to-head) battle with the Mets for a Wild Card spot, Manaea’s season turned around on July 25, when he watched Sale strike out nine across 7 1/3 two-run innings at Citi Field. Watching Sale, a lefty of similar height but with a low release point, motivated Manaea to try something similar. It’s not hard to see where he started, is it?

Manaea, who’d been releasing from around 25° in the first part of the year – remember again, 90° is straight overhand and 0° would be sidearm – is now down to 15° in September. It’s not quite as low as Sale’s 12°, but it doesn’t need to be, either. The point isn’t to be “exactly Chris Sale,” it’s to find what works for Manaea. And it has: he carried a decent 3.74 ERA into that game where he watched Sale, yet he’s been a spectacular 2.63 ever since, with a mere .155/.215/.283 line against.

If he was trying to imitate Sale, it’s hard to argue that it hasn’t worked:

RHP Zack Wheeler, Phillies

Wheeler, by some measures the most valuable pitcher of the last seven seasons, didn’t necessarily need to change anything at all. But he’s always been a tinkerer – he seems to arrive at camp with a new pitch every year – and he’s steadily become something akin to Skenes, dropping down about 3° per year since 2021, as this illustration from MLB.com’s Alex Fast clearly displays.

While we only have data here since 2020, there’s evidence Wheeler has been making changes for years before that, too, with talk about him working on such things in both 2015 and 2018. (“I always like mixing things up, springing new stuff to the plate so that hitters are on their toes,” he told FanGraphs this spring.)

Now, his sinker is getting more horizontal movement, five more inches than he got when he first came up, and he’s pairing it by throwing his four-seamer higher in the zone – getting to that approach angle bonus that we mentioned above.

It all makes for a deadly combination for hitters -- and that's how you lead the Majors in pitching WAR for a half-decade.

LHP Framber Valdez, Astros

Sometimes, dropping down isn’t about trying something new. It’s about getting back to where you were. Between 2018-’22, Valdez was the sport’s pre–eminent groundballing starter, putting 67% of batted balls on the ground when no one else was even at 57%. But something went wrong last year, as his grounder rate sunk all the way down to 54% – still above-average, yet considerably less than usual for Valdez.

It was in part easy to see what was happening; Valdez’s classic sinker was getting 4-5 inches less drop on its way to the plate. That wasn’t all bad, because it was coming in at a career-best 95.3 mph, well above the previous year’s 93.9 mph, and more velocity means less time for the pitch to drop. But the pitches began to flatten out – this is literally what manager Joe Espada said after one particularly poor outing, that “when you start seeing fly balls out of Framber’s performance, you know his stuff is starting to flatten out in the zone” – and the end result was not one of his better seasons.

It was clear, too, that his relatively consistent arm angle had shot up to a much higher slot.

As a strong Baseball Prospectus breakdown last summer pointed out, “Framber is getting behind the ball a lot more than he used to, and inducing more vertical movement on a pitch meant to stay low in the zone,” which is exactly what was happening. Then this spring, Astros pitching coach Bill Murphy was quite clear about what they were trying to do with Valdez in 2024.

“He was definitely yanking out and raising his arm slot, maybe trying to throw too hard,” Murphy said. “That flattened the sinker. So that’s something we’ve definitely been trying to work on, getting him to trust the delivery that he has and allowing the movement to take over.”

The arm slot is back to where it was in 2022. So is the velocity. So is the sinker movement. The ground-ball rate is back up to 60%. This is the Valdez he was meant to be.

RHP Kenley Jansen, Red Sox

While dropping down does seem to be having something of a moment, we can’t stress enough that it’s not a one-size-fits-all solution for all problems. Sometimes, you want to get that arm back up. In Jansen’s case, he’s always been over the top; in fact, in 2022, he was the most over-the-top pitcher in the game, with a 72° arm angle. But in 2023, that arm dropped considerably, all the way down to 47°, and while we can’t say definitively that’s the reason that his strikeout rate dropped to a career-low 27%, it’s hard to ignore.

It was so clear that even without this data available, it was noticeable when we wrote about Jansen back in May 2023, wondering if this was (reasonably!) the beginning of a new phase for a then 35-year-old pitcher.

Jansen knew it, too, talking to MLB.com this spring about trying to get his arm slot right, and it’s really, really difficult to ignore how much the movement on his signature cutter dropped last year – before rebounding this year.

Kaleb Ort, Astros RHP

We recently focused on Ort’s transition from “struggling Red Sox reliever” to “posting an ERA north of 12 with Triple-A Norfolk” to “shockingly good Astros bullpen weapon,” so you can read all about that here. At the time, the most interesting thing was the velocity he’d added, and the cutter he’d prioritized.

But the fastball didn’t just add velocity, did it? By FanGraphs’ Stuff+ metrics, it went from good to great -- and by “great,” we mean “rated as the third-best fastball behind only Emmanuel Clase and Estrada.” That’s about throwing 97.5 mph, sure. It’s also about the rise, the kind that (depending on how you measure such things) makes it a top-five rising fastball, while also losing some of that cut.

It’s not surprising to see, then, that Ort is also throwing more over the top, with one of the largest year-to-year arm angle increases we’ve seen.

Ort, it turns out, isn't just throwing harder. He's releasing higher. He's getting more rise. If he seems like he's throwing a different fastball now, well, he very much is.

Now: If this all sounds space-age and next-level, well, it largely is. But there’s this, too, with a name we’ve redacted for effect.

“As a full sidearm pitcher, [pitcher’s] fastball bears in on right-handers as though there was something personal between them, but left-handers can shoot it like pool … to counter this weakness, he has learned to deliver his pitches from the three-quarter position midway between sidearm and overhand. We've been working on that for years," says [pitching coach Joe] Becker, "and I think he's finally mastered it."

That was from Sports Illustrated, about Don Drysdale. The quote was from 1962. He’d been a good pitcher before, but that year, at 25, he won his only Cy Young Dward and kick-started his Hall of Fame career. Pitchers have been trying to work on their arm angles since basically forever. The only thing that’s different now? It’s a little easier to measure them.