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 »
