Hunter Bigge’s baseball career was in limbo when he graduated from Harvard University in 2021 with a degree in physics. Drafted in the 12th round by the Chicago Cubs two years earlier, the 26-year-old right-hander had scuffled in High-A and was unsure if he should continue to pursue his boyhood dream or move on to a career outside of baseball. Returning to the Ivy League institution to complete his studies following that difficult season gave him options, but he still loved the game.
Fast forward to 2024, and Bigge was thriving in the big leagues.
Bigge debuted with the Cubs on July 9, then a few weeks later was dealt to the Tampa Bay Rays along with Ty Johnson and Christopher Morel in exchange for Isaac Paredes. He excelled in both uniforms. With 15 of his 19 appearances coming after the trade, Bigge worked 17 1/2 total frames, fanning 24 batters while allowing 17 hits and just five free passes. Moreover, he posted a 2.60 ERA, a 2.76 FIP, and a 32.9% strikeout rate. His heater played a huge role in his success. At 97.5 mph, it ranked in the 94th percentile among his contemporaries.
Bigge discussed his path to the big leagues, and his approach on the mound, during the final weekend of the 2024 season.
———
David Laurila: Let’s start with one of my favorite icebeaker questions: Do you approach pitching as more of an art, or as more of a science?
Hunter Bigge: “I approach it more as an art. I’m pretty analytical, but I don’t think the analytical part of my brain is the one that allows me to play the best. I try to come at it with a little more flexibility. I let the science inform the high-level decisions, but when I’m out there, I’m thinking of it more like a dance with the hitter.” Read the rest of this entry »
Nobody wants to throw a backup slider. They are, definitionally, an accident. But announcers and analysts alike have noted that these unintentional inside sliders — perhaps due to their surprise factor — tend not to get hit. In 2021, Owen McGrattan found that backup sliders, defined as sliders thrown inside and toward the middle of the strike zone, perform surprisingly well.
I’ll add one additional reason these pitches are effective: They move more than any other slider.
I analyzed over 33,000 sweepers thrown by right-handed pitchers in the 2024 season. I found a clear linear relationship between the horizontal release angle of a sweeper and the horizontal acceleration, better understood as the break of the pitch. On average, as the horizontal release angle points further toward the pitcher’s arm side, the pitch is thrown with more horizontal movement.
Josh Hejka, a pitcher in the Philadelphia Phillies minor league system, told me these results corresponded with his anecdotal experience.
“I’ve often noticed — whether in game or in the bullpen — that the sliders I throw arm side tend to actually have the best shape,” Hejka said. “I believe it’s conventional wisdom across baseball that the backup sliders tend to actually be the nastiest.”
Check out all the movement Corbin Burnes gets on this backup slider from last season.
The relationship between horizontal release angle and movement also holds true for sinkers. When a sinker is aimed further to the glove side — for pitchers facing same-handed hitters, this would be a backdoor sinker — the pitch gets, on average, more horizontal movement, as is the case with this pitch from Anthony Bender.
The explanation for the relationship is straightforward enough. When sweepers are thrown to the arm side and sinkers are thrown to the glove side, the pitcher’s grip is such that maximum force is applied to the side of the baseball, allowing for more sidespin. In a 2015 interview with David Laurila, then-Royals pitching coach Dave Eiland described why sliders back up.
“They really get around it; they don’t get over the top and pull down,” Eiland said. “It’s unintentional, more of a misfire, so to speak. If you could do that intentionally, you’d have a decent pitch.”
It isn’t just sweepers and sinkers that show a relationship between release angles and movement. Back in August, I investigated the mystery of the invisible fastball. Why was a pitch like Shota Imanaga’s fastball, with its elite vertical movement and flat approach angle, so rare? I found that vertical release angles mediate the relationship between both variables. A fastball thrown with a flatter release angle gets less backspin, and so to achieve both requires outlier mechanical skills.
Release angles don’t just measure the nature of a grip, they also dictate the location of the pitch. I conclude that where the pitcher aims a pitch changes the way it moves. For fastballs, pulling down on the ball allows for more backspin. For sweepers and sinkers, getting around the ball allows for more sidespin. Analysts attempt to separate “stuff” from “location;” these findings complicate that conversation.
***
Before we go any further, it’s important to know what exactly is a release angle. Release angles measure — or, in this case, approximate — the angle at which the ball comes out of the pitcher’s hand. For vertical release angles, anything above zero degrees suggests the ball is pointing upward at release; most vertical release angles, particularly for four-seam fastballs, are negative, meaning that the pitcher is aiming the ball downward at release.
Horizontal angles work the same way, but in the x-dimension. Positive values mean the ball is pointed toward the pitcher’s left; negative values point toward the pitcher’s right. (This is a feature of the original Pitch F/X coordinate system, when it was determined that x-dimension pointed to the catcher’s right.) In any case, release angles, both horizontal and vertical, attempt to capture the exact position of the ball at release. Because they capture the position of the ball at release, they contain information about the pitcher’s aim and, it turns out, the force they’re applying to the ball.
My research finds that there is a relationship between horizontal release angles and horizontal acceleration. In simpler terms, the way the ball is released out of the hand, and therefore where it is aimed, impacts the movement of the pitch.
There are some confounding variables in this specific relationship. The Hawkeye cameras (and, in earlier times, the Pitch F/X technology) report accelerations in three dimensions. These accelerations are measured relative to a fixed point on the field, which happens to be right in front of home plate. Because these accelerations are fixed to one point, the reported values can be biased by the position of release in space. This is far from intuitive, so it might be helpful to consider an example.
Remember that Burnes sweeper from the introduction? It accelerated at roughly 16 feet per second squared in the x-dimension. Imagine that instead of throwing his sweeper from the mound, Burnes threw it from the third base dugout. It’s the exact same pitch as before — same velocity, same horizontal break — but the release point has completely changed. On a fixed global coordinate system of movement measurement, the acceleration in the x-dimension no longer describes the pitch’s relevant movement; all that sideways movement would instead be measured in the y-dimension.
Credit: Filipa Ioannou
This is an extreme example to illustrate the point, but on a smaller scale, this fixed point measurement system biases acceleration measurements. In order to fix this bias, accelerations can be recalculated to be relative to the pitch’s original trajectory, removing the influence of the release point on the acceleration value. These calculations come courtesy of Alan Nathan; Josh Hejka rewrote them as Python code, making my job easy.
A slight nuance:
The accelerations given by MLB (ax, ay, az) are biased by pitch location.
To make these values location-agnostic, we need to adjust the acceleration vector to be relative to the initial trajectory (i.e. the initial velocity vector vx0, vy0, vz0).
Even after accounting for these confounding variables, the relationship between release angles and movement is still present. As the plot shows, it isn’t a particularly strong relationship — when modeled, a two-degree change in horizontal release angle is associated with roughly a foot per second increase in transverse acceleration. But while the relationship is not as strong as that between four-seam fastballs and vertical release angle, it is nonetheless meaningful.
Alternatively, the relationship can be measured using good old-fashioned “pfx_x,” or horizontal movement, which is also measured relative to the pitch’s original trajectory. Why go through all this effort to transform the accelerations? For one thing, I had a good time. And also, isn’t it fun to imagine Burnes throwing sweepers from the dugout?
The plot of horizontal location and horizontal movement, with each pitch colored by its horizontal release angle, illuminates the ostensible lack of a relationship between pitch location — measured by “plate_x” on the plot below — and movement. Draw your attention to the patch of dark blue dots around the -2 line of the x-axis. There are two potential ways for a sweeper to end up two feet off the plate inside. It can be thrown with a horizontal release angle around zero and little sideways movement, or it can be thrown with a negative horizontal release angle and lots of sideways movement.
The same relationship holds true for horizontal release angles and two-seam fastballs after the aforementioned adjustments.
On the individual pitcher level, the relationship is slightly weaker; on average, the r-squared is roughly 0.04 for sweepers, with variation between pitchers on the strength of this relationship. Zack Wheeler’s sweeper movement, for example, appears to be particularly sensitive to release angles:
***
Ultimately, analysts attempt to separate “stuff,” defined as the inherent quality of a pitch, from “location,” defined as where the pitch ends up. But what this research suggests is that, to some degree, these two qualities are inseparable. (I wrote about this a bit on my Pitch Plots Substack last September.) Certain pitches generate their movement profiles because of where they’re aimed out of the hand.
These findings naturally lead to deeper questions about the interaction between biomechanics and pitch movement. While there are variables (arm angle, release height, etc.) that are commonly understood to influence movement, these findings suggest that there are even more granular factors to explore.
Is the angle of the elbow flexion at maximum external rotation the most influential variable? Is it hip-shoulder separation? Torso anterior tilt? Pelvis rotation at foot plant? How much do each of these components contribute to pitch shapes?
Thanks to data from Driveline’s OpenBiomechanics Project, it’s easy to model the relationship between dozens of biomechanical variables and the velocity of the pitch. There are about 400 pitches in the database; by attaching markers to a pitcher moving through space, points of interest can be calculated and then compared to the pitch’s velocity.
In this public dataset, Driveline does not provide the movement characteristics of the pitch. But if the force applied to the ball based on the direction of its aim affects the movement of the pitch, it follows that these variables could be measured in a detailed manner. On the team side, KinaTrax outputs provide the markerless version of these data, providing a sample of hundreds of thousands of pitches from a major league population. Imagine the possibilities.
Correction: A previous version of this article misstated the units of acceleration of Burnes’ backup sweeper. It is feet per second squared, not feet per second.
Ben Lindbergh and Meg Rowley banter about the start of spring training games, the charms of Tigers reliever John Brebbia, whether MLB’s uniform pants were always semi-transparent, and Shohei Ohtani’s parallel parking skills. Then they preview the 2025 Seattle Mariners (27:37) with Ryan Divish of The Seattle Times, and the 2025 Cincinnati Reds (1:12:53) with The Athletic’s C. Trent Rosecrans.
Wrights_Back: What would the Mets have to give up to get Cease – if he is available?
12:02
Dan Szymborski: I think the closer we get to the season, the more the Padres will hang onto him.
12:03
Dan Szymborski: The Mets would certainly have to give up something real. YOu can probably fatten the offer a bit with guys the Padres have more reason to like than the Mets.
12:04
Dan Szymborski: Like Clifford, who is probably more useful to San Diego, but you’re not going to land him with JUST Clifford
12:04
Dan Szymborski: I kinda get the idea that the mets are happyw ith their rotation, and not likely to meet a rich price
Spring is the time of year when we wax poetic about possibility. “Behold,” we say to ourselves as we remember the feeling of the sun’s warmth on our skin, “we have once again foiled the earth’s attempts to murder us with subzero temperatures and an unceasing barrage of unrelentingly cheery and/or horny Christmas songs. The time for survival is past; now is the time to thrive.” Among baseball players, pitchers stand alone in their capacity for reinvention. They have the chance to add a new weapon, and in so doing level up into an entirely new pitcher. After all, what are we if not a collection of our attributes? Maybe you used to be a sinkerballer, but once you added a slider, you evolved into an entirely new species: the sinker-slider guy.
I spent Wednesday afternoon trawling through search results and Jeff Zimmerman’s indispensable Mining the News feature looking for reports of new pitches. The fruits of that labor populate the table below, and they are legion. As it turns out, even MLB: The Show has finally added a sweeper. Beneath the table, I will spend a sentence or three on each of the 21 pitchers who is reportedly working on a new offering. Not all of these pitches will actually make it into a regular season game. Fewer still, possibly even none, will have a discernible impact on a player’s season or career. But that shouldn’t keep us from dreaming on them. There are some really big names here. Maybe Kevin Gausman’s new cutter will run interference for his four-seamer, returning him a while longer to the fraternity of undisputed aces. Who are we to deem any future unreachable before even attempting the journey? Read the rest of this entry »
For the third consecutive offseason, Justin Turner has signed to play for a new team. This time, he is heading to the north side of Chicago, after he and the Cubs agreed to a one-year deal worth $6 million earlier this week. Turner, who turned 40 in November, will likely split time at DH and 1B. The reason to add Turner at this stage in his career is straight forward: He can still hit at an above league average clip.
Considering Turner is entering his 17th major league season, you likely already know a lot about his game. His whiff and strikeout rates have stayed in the upper quartile even as he has aged, he doesn’t chase much, and has a great feel for spraying the ball to all fields. It’s the exact group of traits that a hitter without much explosiveness needs to survive this many years. Here is a quick reminder of his performance over the last handful of years to put into perspective where he is at right now:
Old Man Turner’s Still Got It
Season
wRC+
K% Percentile
Whiff% Percentile
Chase% Percentile
xwOBACON
VBA
2021
126
80th
88th
83rd
.383
36.9
2022
123
78th
78th
65th
.367
34.9
2023
115
77th
92nd
71st
.367
34.4
2024
117
74th
90th
72nd
.343
34.2
There is no doubt his contact quality has dipped. That’s likely a function of his bottom decile bat speed. But along with that has come improved whiff rates. This compensation represents a new version of how Turner has been successful with his current physical attributes. It’s a benefit to any team to plug in this type of hitter, especially because he is productive and essentially platoon neutral.
To be frank, though, I don’t think a full on, comprehensive analysis of Turner’s offensive game is completely needed at this point. We’ve seen what he can do and have a good idea what type of hitter he is now. Instead, I want to use this time to highlight what I think is the most impressive part of Turner’s game, the part that makes me enthusiastic to watch him in the twilight of his career: His ability to hit sinkers. Read the rest of this entry »
It’s common for readers to ask which of the players who aren’t on this year’s Top 100 might grace next year’s edition. Who has a chance to really break out? This is the piece for those readers, my “Picks to Click,” the gut-feel guys I think can make the 2026 Top 100.
This is the eighth year we’ve conducted this exercise at FanGraphs, and there are some rules. First, none of the players you see below will have ever been graded as a 50 FV or better prospect in any of our write-ups or rankings. Second, I can’t pick players who I’ve picked in prior years, though I can take players who other writers selected and I didn’t. For instance, I picked Jackson Baumeister last year, but he didn’t make the Top 100. I can’t select him again, but I would if I could. Brailer Guerrero made the Top 100 in the middle of last season, and then hurt his shoulder for the second time in two years and fell off. I can’t put him on here, no matter how much I like him. Read the rest of this entry »
It seems like just last week that Guerrero brought his bonkers power and elite hit tool up to the majors, but time flies. Should Guerrero choose to play elsewhere next season, losing him would be a definitive moment in Blue Jays history. Not just because of his star power and the hype that accompanied him since he first signed with the team as an amateur free agent, but because he’s Toronto’s best player by far. Read the rest of this entry »
As we’ve seen with the FanGraphs Depth Charts and ATC, averaging projections from multiple systems is a common approach for improved accuracy when forecasting performance for the current season. This article applies the same “wisdom of the experts” aggregation logic to combine peak projections from various systems — in this case, ZiPS, Clay Davenport’s projections, and OOPSY — to build a consensus top hitting prospects list.
Overview
Earlier this offseason, I published OOPSY’s top hitting prospects by peak projected major league wRC+. You can check out the article for a detailed explanation of the methodology, but the short version is that peak projected wRC+ is essentially a 2025 projection, except with extra aging added to it in order to forecast how good each prospect will be at their (late-20s) peak. Read the rest of this entry »
Ben Lindbergh and Meg Rowley banter about a player who signed an extension (Geraldo Perdomo), a player who didn’t sign an extension (Vladimir Guerrero Jr.), a player who’s switching positions (Mike Trout), and a player who’s not switching positions, at least for now (Rafael Devers), plus an update on Meg’s updated beliefs about Shohei Ohtani’s dog. Then (48:42) they talk to Eric Longenhagen about FanGraphs’ top 100 (well, 102) prospects list and much more.
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Dan Szymborski
