Everyone thought it was gone. Jurickson Profar hopped around, ostensibly upset that Mookie Betts’ fly ball had dropped into the left field seats. The camera panned to Betts triumphantly rounding the bases. The scorebug flipped from zero to one under the Dodgers logo. And then, a few seconds later, all was clear: Profar had pulled a Julio Rodríguez, fooling everyone into thinking it was a homer before whipping the ball back into the infield. He wasn’t hopping out of frustration, it turned out; on second look, he was engaging in some well-earned taunting, goading the assembled Dodgers fans after his excellent defensive play.
Profar’s first-inning home run robbery and subsequent gloating was a sign of things to come. In a tense clash between these two Southern California rivals, the Padres came out on top, 10-2, to level the NLDS at a game apiece, battling their opponents both on and off the field throughout the course of this bizarre evening.
The weirdness peaked in the seventh inning, when the game was delayed for over 10 minutes while fans threw things — including baseballs and beer cans — onto the field, pausing the action. While security guards attempted to get the crowd under control, Padres manager Mike Shildt gathered his fielders, issuing a fiery impromptu pep talk as the team huddled around their appointed leader. After the inning, an even larger group meeting was held in the Padres dugout, this time led by the on-the-field leader, Manny Machado, who issued marching orders to the rest of the San Diego roster. Read the rest of this entry »
As Gunnar Henderson stepped to the plate in the bottom of the ninth inning of Game 2 of the AL Wild Card Series on Wednesday night, his team down by a run and one out from elimination, it felt like something special was brewing. Late-inning tension, high stakes, one of the sport’s biggest stars: The postseason was peaking, and the young superstar held the Orioles’ fate in his hands, poised to deliver a signature moment. Unfortunately, he had to deal with Lucas Erceg’s changeup.
I’ve followed Erceg all year, first from afar, mystified by the flamethrower that materialized out of nowhere in the Oakland bullpen, and then with a closer eye when he moved to Kansas City, watching him slip seamlessly into the fireman role in the Royals bullpen. His eye-popping fastball velocity caught my attention, but it’s the changeup stealing the show on the bright October stage.
Lucas Erceg Pitch Specs
Pitch Type
Induced Vertical Break (in.)
Horizontal Break (in.)
Release Height (ft.)
Velocity (mph)
Usage (%)
Changeup
6.7
-17.9
5.9
91
19.9
Four-seamer
15.1
-10.1
6
98.6
30.9
Sinker
10.2
-15.8
6.1
98.5
21.3
Slider
-3.1
-0.1
6
85.7
27.9
SOURCE: Baseball Savant
As the table shows, Erceg’s velocity sits at the top of the scale. His four-seam fastball averages 99 mph. Again, he sits at 99 mph. But the results on it were just so-so: It graded out at 0.1 runs per 100 pitches by Baseball Savant’s run value calculations, neither helping nor really hurting him.
I think the pitch’s performance can be explained by its exceedingly “normal” shape. (Shout out to Leo Morgenstern.) Erceg throws his fastball from a 43-degree arm angle, which is smack dab in the tall part of the histogram among major league pitchers. From that bog-standard arm angle, his fastball gets roughly league-average induced vertical break.
Max Bay’s “dynamic dead zone” application projects how batters might perceive Erceg’s fastball relative to arm angle expectations. While the pitch drifts further to his arm-side than batters might initially expect, the vertical expectations are basically identical. The conventional shape of his four-seam fastball knocks it down a peg from a “stuff” perspective, taking it from plus-plus to maybe just plus.
But a high-velocity fastball doesn’t exist in a vacuum — it exists in the context of all in which it lives and what came before it. In other words, it impacts all of the other pitches in an arsenal. As Erceg rears back to throw, hitters have to keep that 99 mph in mind. And that expectation will certainly help a changeup play up.
The velocity separation between his four-seam fastball and changeup is solid — Erceg’s changeup averages 91 mph — but the horizontal movement of the pitch is its most distinct quality. It averaged 17.9 inches of horizontal movement this season; of the 165 pitchers who threw at least 150 changeups in the regular season, only three averaged more horizontal movement, putting Erceg in the 98th percentile.
Some of that arm-side fade is seam-shifted-wake effects; some of it is connected to Erceg’s motor preferences. (Mario Delgado Genzor wrote a great primer on motor preferences for Baseball Prospectus in January.) Erceg, as far as I can tell, is a pronator, which means that his natural throwing motion is conductive to changeups that run and fade to the arm side. Watch how he whips his forearm toward his body in the slow-motion part of this video:
In these playoffs, at least, it’s been not just the movement that’s exceptional, but his pinpoint command of the pitch. On that 1-2 changeup to strike out Henderson, he buried it in that perfect location right below the knees, where it looks like a low fastball right up until the point that it isn’t.
What makes one changeup better than another is generally one of the more difficult questions to answer in pitching analysis. Royals ace Cole Ragans, for example, had one of the best changeups in baseball this season. Its effectiveness can’t really be explained by its shape — it doesn’t have much depth or movement differential from the fastball. But hitters, time and again, swing through the pitch, deceived by Ragans’ arm action or the way the trajectory mirrors his fastball or some other variable that is impossible to measure. Unlike a fastball, a changeup cannot be easily graded by a stuff model because it depends on how it plays against the expectations of the fastball.
What makes Erceg’s changeup good, however, seems pretty obvious to me. It goes fast and it moves a ton, almost like a lefty slider.
The changeup helps Erceg stand above other relievers with more limited arsenals. Against righties, he is mostly a sinker-slider guy, throwing his two-seamer in on the hands and then dropping his slider below the knees for whiffs. But against lefties, he relies on his four-seamer and changeup, neutralizing lethal lefties like Henderson. The results bear this out — Erceg faced roughly an equal amount of righties and lefties this season and held them both in check (.242 wOBA against righties, .279 wOBA against lefties).
There is a flip side to extreme pronation: It is hard to throw big, sweepy glove-side breaking balls. And yet Erceg’s slider has actually graded out as his best pitch by run value and whiff rate this season. As Erceg’s pitch movement plot shows, befitting his pronation bias, the slider doesn’t actually get any glove-side movement, coming awfully close to achieving a true “deathball” shape. Note the yellow dots representing the sliders he threw this season:
Even without glove-side movement, that shape can still be super effective. When Kumar Rocker made his debut, some analysts were throwing 80 grades on his “deathball” slider. Erceg’s slider is shaped just like Rocker’s, but Erceg throws his a couple miles an hour harder.
Erceg’s top-end velocity, platoon-neutral arsenal, and rapidly improving command (a 14.3% walk rate in 2023, an 11.9% walk rate when Michael Baumann wrote about him in May, and a 4.4% walk rate since that post) suggest to me that he could make a transition to starting pitching. Even if he drops two or even three miles per hour while stretching out to six-inning appearances, the fastball velocity will still be well above average. And if the Royals do decide to go that route, they could accrue significant benefits without risking too much. According to Roster Resource, they have him under team control through the rest of the 2020s, giving them plenty of opportunity to reverse course if it doesn’t work out.
Lucas Erceg, quality major league starter — it’d be quite an ending to a remarkable story. He was drafted by the Brewers as a third baseman in 2016, but after struggling to hit in the high minors before and after the pandemic, Erceg made the switch to pitching. Just 18 months ago, our lead prospect analyst Eric Longenhagen wrote that “his mechanical inconsistency impacts his fastball location,” but noted that Erceg had a “chance to make a consistent big league impact if things click for him command-wise.” He is still so new to this, and so it is easy to imagine what could be.
But all of that is for the future. Right here, right now, in the heart of the playoffs, Erceg is the primary weapon out of a surprisingly solid Kansas City bullpen. And it’s the changeup, in my view, that is setting him apart.
Martijn Verhoeven wears many hats. As the research lead for the Twins sports science department, he is in conversation with all sorts of people, including baseball operations staffers, coaches, hitters, pitchers, and the medical staff. Verhoeven is armed with biomechanical data from KinaTrax, and the insights from the data help all these people do their jobs.
For understandable reasons, the Twins want to keep these insights private. Baseball is a zero-sum game — only one team can win the AL Central, and so the Twins would prefer their divisional opponents not know what they’re thinking.
But there is one area where this tendency for teams to hunt competitive advantages might be working against their interests: identifying solutions to the pitcher injury crisis.
“We have this massive injury epidemic,” Verhoeven told me. “There are times where I wish [teams] could share more and collaborate more because ultimately I think everyone would benefit from just having the best players on the field longer and more often. You can tell that people who’ve worked with this data for a long time are sort of moving toward [asking], ‘What can we do from a collective point of view in terms of making some of this understanding available?’” Read the rest of this entry »
If I’ve learned anything from the new Statcast bat tracking data, it’s that bat speed alone isn’t sufficient to produce a high-quality major league hitter. Johnathan Rodriguez, Trey Cabbage, Zach Dezenzo, Jerar Encarnacion — all of these guys, at this early stage of their major league careers, swing hard but miss harder. Bat speed only matters when you make contact.
When you do hit the ball, however, it’s nice when your swing is as fast as possible. Swinging fast while making good contact most of the time — it’s hard to do, but if you can do it, you’re probably one of the best hitters in baseball.
The reason it’s rare is because these two variables — swinging hard and making solid contact — are negatively correlated. As some probably remember from when these stats originally dropped, Luis Arraez swings the slowest and squares up everything, while Giancarlo Stanton swings the fastest but seldom connects. A slow swing is a more precise swing, and so the group of hitters who can swing precisely while letting it rip are uncommon.
Podcasts hosted by athletes — I don’t know about all that. But I did enjoy a recent clip from Mookie Betts’ podcast where he was talking to Cal Raleigh, who was comparing Zack Wheeler — perhaps the best pitcher in baseball — to his batterymate Bryan Woo.
“[Wheeler] is kind of like Woo,” Raleigh said. “He glides down the mound. And it’s so effortless. Some guys just have that natural glide down the mound, easy, and [the ball] just gets on you.”
Coincidentally, in a conversation in late August, Phillies minor league pitching coach Riley McCauley made the same comparison.
Pedro Avila might not strike you as exceptional. He’s mostly on mop-up duty in the Guardians bullpen, hoovering up low-leverage innings. His sinker was deemed the “most normal” in baseball by Leo Morgenstern earlier this year. And his 3.60 ERA and 3.92 FIP is right around average for major league relievers.
But behind this veneer of normalcy lies the weirdest changeup in baseball.
Below is a plot of the average vertical and horizontal moment of every pitcher’s changeup during the 2024 season (minimum 50 changeups, data as of August 15, vertical movement measured without gravity). You have a 50/50 shot of guessing which one is Avila’s:
The brown dot on the left of my beautifully drawn circle is Logan Allen’s changeup, Avila’s erstwhile teammate. Michael Baumann wrote about Allen’s “weird-ass changeup” last July, noting that the pitch had the least horizontal movement of any major league changeup in the 2023 season. (Unfortunately, despite Michael’s request, no “Weird-Ass Changeup World Tour” tag has since been added to the CMS.) The purple dot on the right is Avila’s changeup, which is averaging even less horizontal movement than Allen’s.
But the average movement profile doesn’t fully capture what’s weird about Avila’s changeup. To truly appreciate the weirdness, it is necessary to take a look at why it moves like that.
It starts with his crazy grip. Look at this grip!
He aligns his thumb and pointer finger in a quasi-circle-change grip while pressing on the exact opposite side of the ball with his other three fingers. The funky grip — a circle-change/splitter/forkball/vulcan-change hybrid — informs the way the ball comes out of his hand.
Scott Firth, a former performance coordinator at Tread Athletics, described Avila’s grip in a tweet from January 2023 and the movement profile that results from it.
“Looks like fosh/modified box grip, some guys will cut it hard with 3 fingers on outer part of ball,” Firth wrote. “Low spin low efficiency could catch ssw [seam-shifted wake] either direction depending on cw [clockwise] or ccw gyro.”
The contradictory forces of fade from the pronation and cut from the pressure of his three fingers results in chaos; because of that grip, the ball comes off the pointer finger and middle finger simultaneously, sending the pitch downward:
Avila’s changeup almost imitates a knuckleball in the randomness of its spin axis. A helpful way to understand this is by looking at Avila’s spin-based movement and observed movement. The spin-based movement is the orientation directly after release; the observed movement is the implied axis based on the movement of the pitch. (When the spin-based orientation does not match the observed orientation, it is generally assumed that “seam-shifted wake” is responsible. More on that later.)
The observed spin axis on Avila’s changeup nearly goes around the entire clock. Check out the green bars on the graphic below:
Avila’s changeup might ultimately move similarly to Allen’s from a “shape” perspective, but the aesthetic experience from the hitter’s vantage point is distinct. It’s a complete outlier from the perspective of spin efficiency, defined as the percentage of spin that is either sidespin or backspin/topspin. The median changeup is 95% spin efficient. Allen’s changeup has 72% spin efficiency, one of the lowest marks in baseball. Avila’s changeup checks in at 24% (!!) spin efficiency, which is more like a typical gyro slider than any changeup.
The Guardians broadcast picked up on this following a slow-motion replay of an Avila changeup. After watching the replay, Guardians color commentator Rick Manning remarked that “It’s almost like a forkball but he spins it like a slider.”
Perhaps it goes without saying, but this is not the traditional way to throw a changeup. Driveline, for instance, published an article showing five different grips for aspiring changeup-throwers to try; none of them resemble Avila’s.
The classic changeup is thrown with heavy pronation. Think Logan Webb’s changeup fading down and away from a left-handed hitter:
Some pitchers struggle to throw a changeup with heavy pronation. One key reason, as Noah Woodward pointed out in a March 2023 post, is that the act of “turning over” the ball is awkward for pitchers who don’t throw another pitch that requires turning over their wrist in the manner required of a Webb-esque changeup.
For pitchers like Tarik Skubal or Matthew Boyd with more of an inherent supination bias, the seam-shifted wake changeup is a way to throw an offspeed pitch without contorting their arms in uncomfortable directions.
“I throw a changeup just like a slider now, but using essentially the smooth part of the baseball to create no drag on one side, but seam is on the other side,” Boyd told MLB.com’s Jason Beck in March 2023. “And because of that, I get more movement than I did before, but the pattern of how my wrist is moving is like the other pitches. So it allows for the other pitches to be more consistent.”
Avila’s changeup does not fit neatly in either of these categories. It is, somehow, a pronated seam-shifted wake changeup. That explains why Avila leads the league in the gap between his changeup’s spin-based axis and his observed axis.
But that gap doesn’t tell the whole story. Most other pitchers have a similar pattern when their actual spin orientation deviates significantly from the “spin-based” orientation: It shifts to the left (or right) in a predictable pattern. Take Skubal’s seam-shifted wake changeup, for example. The “observed spin” is shifted to the left of the spin-based movement.
Avila’s changeup is not like that. Because of the heavy gyro spin that his grip produces, the pitch leaves the hand at somewhat random orientations and can either fade or cut, as the movement map of all his changeups in 2024 shows. Notice how the green dots (his changeups) can end up on either side of the pitch plot:
So Avila’s changeup is definitely weird, but is it good? It certainly produces some bizarre swings, even when it’s poorly located. Heliot Ramos, for one, looked flummoxed after whiffing on one middle-middle Avila changeup:
Avila’s changeup gets a lot of whiffs — among changeups thrown at least 100 times, his ranks in the 85th percentile in swinging strike percentage and the 78th percentile in whiffs per swing. On the other hand, he throws one out of every six changeups in the “waste” zone, which sort of makes sense to me — that grip feels prone to misfires. (Shout out to Alex Chamberlain’s pitch leaderboard for these stats.)
While Avila’s changeup has graded out as basically average from a run value perspective, I’m not always sure that run value is the best way to evaluate the quality of a given pitch. There are interaction effects between pitches — in other words, the thought of the changeup in the batter’s mind might improve the quality of his fastball — and Avila is using the changeup as his primary out-pitch and getting pretty good results.
Given that the Padres DFA’d Avila in April, this season looks like a success for him, and the changeup is without question a big part of all that. As always with pitching, weird is where you want to be.
This is Michael Rosen’s first piece as a FanGraphs contributor. You may have read his previous work at the site, including his article about the Kirby Index, a metric he created to measure command using release angles. He lives in Los Angeles and works as a transportation planner.
Earlier this year, I tried to solve the riddle of howShota Imanaga threw his invisible fastball. The pitch had (and still has) a rare combination of traits: At the time of writing, only Imanaga and Cristian Javier threw fastballs from super flat vertical approach angles (VAA) with elite induced vertical break (IVB). A fastball with a flat VAA or high IVB plays a trick on the hitter’s perception; a fastball with both qualities becomes nearly unhittable, or invisible, when located at the top of the zone. I posed two questions in that piece: Why was this invisible fastball so rare? And what was Imanaga specifically doing to throw a fastball with these traits?
The first question can be answered, my research shows, by looking directly at release angles. Release angles reflect the direction that the pitcher is aiming the ball at release, which I wrote about at length in my article on the Kirby Index from May. That act of aiming — specifically, the direction the ball is oriented out of the pitcher’s hand — also affects the amount of backspin on a four-seam fastball. Read the rest of this entry »
George Kirby had Javier Báez right where he wanted him. It was October 3, 2022, the last start of Kirby’s excellent rookie year, and Kirby had Báez, the king of chasing sliders off the plate, in an 0-2 count. His catcher, Cal Raleigh, set up off the plate, suggesting that Kirby would be targeting the outer edge.
Kirby hit his target with a well-executed slider. And Báez, instead of whiffing, hit it out of the park.
Báez wasn’t fooled; at seemingly no point did he think that pitch was a fastball. And Kirby’s lack of deception — defined here as a lack of overlap between the horizontal release angle (HRA) of his fastball and slider — may have played a part. Read the rest of this entry »
On the first knuckleball thrown at Coors Field in 16 years, Matt Waldron hit home plate umpire Bill Miller right in the nuts.
Nobody — not Waldron, not his catcher Kyle Higashioka, not Miller — appeared to know where the ball was going. Despite Higashioka frequently (and understandably) struggling to track the flight of the ball throughout the rest of the night, Waldron delivered a career-best performance, allowing just one run over six innings.
Perhaps the most surprising part of his performance was the setting. Since 2008, knuckleballers have dodged outings at Coors Field, which sits 5,200 feet above sea level. Conventional wisdom dictates that knuckleballs at altitude are a bad idea, as Cy Young-winning knuckleballer R.A. Dickey told Dave Krieger back in 2012. Read the rest of this entry »
In the course of researching the haphazard nature of JP Sears’ fastball command for my blog Pitch Plots, I realized I was missing the answer to a fundamental question: Why does the ball go where it goes?
Specifically, I had no idea which variables determine the physical location where a pitch crosses home plate. My first guesses revealed nothing: a combination of velocity, extension, spin, and release height had no relationship to a pitch’s eventual location. If it wasn’t any of these factors, what could Sears change to throw his fastball to better locations?
I was missing the key variable: the release trajectory. Trajectory, as defined here, is not just release height and width but also the vertical and horizontal release angles of the pitch, which are not widely available to the public on a pitch-by-pitch basis.
The release trajectory, it turns out, explains nearly everything about the ultimate location of a pitch. Read the rest of this entry »
