If motor preferences were the final word on pitcher performance, Nathan Eovaldi would be sitting on a beach somewhere.
Eovaldi throws from a low slot, releasing his pitches from an average arm angle of 30 degrees. (Zero degrees is fully sidearm; 90 degrees is straight over the top.) Many low-slot pitchers have a supination bias. There are downsides to being a supinator — their preference for cutting the baseball tends to produce crummy four-seam fastballs — but they usually have no trouble throwing hard breaking balls; they can also more easily harness seam-shifted wake to throw sinkers, sweepers, or kick-changes. Low-slot supinators, like Seth Lugo, can basically throw every pitch in the book. High-slot pronators like Ryan Pepiot or Lucas Giolito don’t have that sort of range, but make up for it with excellent changeups and high-carry fastballs.
Eovaldi is, tragically, a low-slot pronator. Not many low-slot pronators make it to the big leagues. The pronation bias blunts their ability to throw hard glove-side breakers, and the low arm angle obviates the pronator’s nominal advantage, killing the carry on their fastball. As Tyler Zombro of Tread Athletics (now a special assistant of pitching for the Cubs) said in his primer video on motor preferences, “I know in stuff models and just off of Trackman alone, this arsenal with this slot is not that attractive.” Read the rest of this entry »
In the introduction to their 2023 Saberseminar presentation, Scott Powers and Vicente Iglesias hit on a fundamental truth about pitching: The variable that bests predicts the outcome of a pitch is the location where it crosses the plate. For a case study, look no further than this tweet from MLB.com’s David Adler about Yoshinobu Yamamoto’s splitters.
Hitters have swung 74 times at Yoshinobu Yamamoto's splitter this season …
If Yamamoto buries his splitter arm side, he’s probably getting a whiff. If it’s on the edge of the zone, it’s likely a foul ball. If it catches plate, it’s getting put in play. The location dictates the outcome.
Given this truth, pitchers who command the ball best ought to dominate. But there’s a catch. As Powers and Iglesias noted, the location is also the variable with the least predictive reliability. If you see a pitcher throw a fastball 98 mph, you can be pretty sure he is going to do it again. A dotted backdoor slider, on the other hand, does not guarantee an entire game of dotted backdoor sliders. Command is both the most important and the least reliable quality for a pitcher.
Scott Powers and Vicente Iglesias, 2023 Saberseminar
Nobody can nail the corners with every pitch. But pitchers can at least minimize the variance of their locations, finding relative reliability within the chaos of command. And in 2025, there is perhaps nobody more reliable than Jacob deGrom.
deGrom’s flat attack angle fastball and firm slider have (justifiably) built his reputation as a stuff monster. Even after easing up on the gas pedal this season, deGrom is still a darling in the eyes of the models. His overall Stuff+ is in the 80th percentile for starters with at least 30 innings pitched, fueled by his depth-y 89-mph slider. PitchingBot likes deGrom even more, ranking him in the top 10 among those pitchers. Over at Baseball Prospectus, the StuffPro model believes deGrom wields four pitches — his curveball and changeup, in addition to the heater and slider — that all grade out as plus.
deGrom’s unbelievable precision came to my attention while writing about Hunter Gaddis for a piece that was published on Monday. As part of my effort to discern whether Gaddis owed his early-season success to slider command (the verdict: inconclusive), I created a version of the Kirby Index for sliders to see where he landed. That metric measured the variance in release angles and release points and distilled those figures into a single score that captured command ability. Originally, it was designed for fastballs, which tend to be thrown to all parts of the strike zone. It perhaps works even better for sliders, which generally are thrown to fewer targets. Gaddis’ rank among his fellow pitchers was nothing remarkable, but deGrom’s name sitting at the very top caught my attention.
Minimum 50 sliders thrown to right-handed hitters.
As I wrote earlier this year, a more straightforward implementation of the Kirby Index would be to just measure the variance of the actual pitch locations. For this story, I calculated the standard deviation of the vertical and horizontal locations of a given pitcher’s sliders; once again, deGrom found himself at the top of the pack. Look at how much distance there is between him and the next closest pitcher:
Minimum 50 sliders thrown to right-handed hitters.
Random tangent here, but you have to admire Luarbert Arias for refusing to throw his junky 82-mph slider anywhere but inside the strike zone.
Anyway, measuring location densities, ultimately, could just point at pitchers who fill up the strike zone; the real test of command is a pitcher’s ability to hit his actual target. To that end, Driveline Baseball provided me with a sample of their proprietary miss distance data. Using Inside Edge tracking data, Driveline measures the distance from the intended target to the actual location of the pitch.
No surprise — deGrom’s slider miss distance ranked first among all pitchers. The league-average miss distance for sliders is about 12.5 inches; this year, deGrom is missing his target by under nine inches, nearly three standard deviations below the average. Any way you slice it, deGrom is commanding his slider like no one else in the sport.
The outcomes have been unassailable. So far, deGrom’s slider has returned a run value of -3.2 per 100 pitches thrown, the best mark for any slider thrown by a starting pitcher. Not only is he getting a bunch of swing and miss — a 38.1% whiff rate, as of this writing — it’s also grabbing a ton of called strikes. When batters do manage to put it in play, they can’t do much with it. The average launch angle on the pitch is just 2°; the xwOBA is a meek .227.
The harmless outcomes on balls in play are a function of deGrom’s targets. To right-handed hitters, he targets the classic low-away corner, breaking off the plate. Note the bimodal distribution on the heatmap — there’s a large concentration of sliders he’ll throw in the zone for strikes, and then another cluster right below the zone that generate chase.
These intentions can be seen in the filtered heatmap clusters. When deGrom throws sliders to righties in zero-strike counts, he tends to be in the zone:
In two-strike counts, he chases the swing and miss:
To lefties, deGrom shows a similar bimodal distribution, but the pattern appears reversed. In early counts, he’s aiming just below the zone; in late counts, he’s looking for called strikes. This sequence to Athletics rookie Nick Kurtz, which featured four sliders, gives a sense of the approach. On 1-0 and 2-0, deGrom tries to bait a chase, but the big lefty resists.
Down 3-0, deGrom fires a middle-middle heater in an auto-take scenario, then returns to the slider in a 3-1 count. Here, deGrom dials in his robotic precision, dotting the lower edge of the strike zone to bring the count full.
On 3-2, he goes there again. Kurtz takes it and pays the price. Though the superimposed strike zone on the broadcast says this pitch is just low, my sense is he deserves that call; if he’s consistently landing pitches within inches of his intended target, you sort of just have to hand it to him.
deGrom isn’t just painting with the slider. I calculated the Kirby Index for four-seam fastballs thrown to righties in 2025; incredibly, he also sits in first place on that list.
Minimum 50 fastballs thrown to right-handed hitters.
As nice as it would be to think that deGrom can be just as good even after dropping two ticks off the fastball, it just isn’t true. Absent improvement elsewhere, losing stuff will bring him back to Earth. But deGrom is far from stagnant. In 2019 — his last full big league season, amid the most dominant phase of his career — his fastball command measured as below average by miss distance. Six years later, it’s hard to argue his command is anything but 80-grade. And as long as the elbow cooperates, it will help him defy gravity.
Random relievers can do crazy things in small samples. Who can ever forget Nationals right-hander Justin Miller striking out 57.9% of the hitters he faced across a three-week stretch of 2018? Or Kody Funderburk’s legendary whiff explosion to close out the 2023 Twins season? Guardians reliever Hunter Gaddis is on one of these incendiary strikeout runs, and it’s driving me to madness.
Gaddis might not strike you as operating at the same level of random as Miller and Funderburk. By any set of reasonable standards, Gaddis broke out last season, appearing in nearly half of his team’s games while delivering a 1.59 ERA. But — forgive me — I didn’t really buy it. His 23.7% strikeout rate matched the league average for relievers, and his arsenal didn’t exactly justify a .205 BABIP. Given his pitch shapes and peripherals, I figured Gaddis would settle in as more of a solid middle-relief type than one of the premier backend arms in the league. And then this April happened. Read the rest of this entry »
It was June 2024, and Matt Bowman was in a tough spot. He was 33 years old and fresh off his third DFA in six weeks. In his one appearance as a Mariner, he recorded just two outs, gave up one run on one hit — a home run — and one walk. As a righty reliever on the wrong side of 30 with a 92-mph sinker, he was about as fringey as they come.
That day in Seattle could have been his last time on a big league mound. Instead, he tried something crazy. Once the owner of an unremarkable delivery, Bowman now throws from the most extreme horizontal release point in the sport. And it looks like it has saved his career. Read the rest of this entry »
First impressions are everything, the expression goes, and a poor one could have doomed Juan Soto’s 2024 season. The Yankees dealt five quality players for one year of his services; a slow start in the Bronx would have invited the wrath of tabloids and fans alike. But Soto started with a bang, gunning down a runner at home plate to preserve a ninth-inning lead in his debut and going on to hit .325/.438/.561 in his first month as a Yankee. From day one, he was undeniable.
This time around, he hasn’t been as lucky. Soto remains in New York, albeit in a different borough, and he’s fresh off signing the largest contract in professional sports history. By those standards, his start this season is underwhelming. His batting line is 25% above league average, but the shape of his production is essentially Soto at his least productive: tons of walks, a few too many groundballs, and not much extra base damage. The quasi-slow start prompted a story written by The New York Post’s Mike Puma headlined “Juan Soto opens up to The Post about pitchers’ new approach without ‘the best hitter in baseball’ behind him.” Read the rest of this entry »
Jayne Kamin-Oncea and John Froschauer-Imagn Images
Hitting a baseball is an unthinkable accomplishment of timing. In order to strike a ball traveling from the pitcher’s hand to the plate in less than half a second with a slab of wood, a hitter must execute an elaborate sequence of movements on time. When do you lift your front foot? When do you load your hands? When do you fire your hips? It’s a sophisticated choreography; a beat late at any point can doom the swing.
Picture Fernando Tatis Jr. When Tatis is at the plate, he shifts around like a predator stalking its prey, eyes peeled for the exact moment when the pitcher lifts his front foot so that he, too, can get his toe down at the right time, and then his hands up, and then finally the barrel through the zone:
If hitting is such a delicate sequence, conditional on the pitcher’s own timing, it follows that pitchers who mess with that timing can improve their performance; by extension, pitchers who groove their deliveries will underperform their stuff. In an interview with David Laurila in 2017, Jason Hammel described changing his delivery for these precise reasons. Read the rest of this entry »
I thought I had it sorted out; it took one batted ball to convince me otherwise. It was the bottom of the seventh inning during the Rays’ first game in their new George M. Steinbrenner (GMS) Field digs. Jonathan Aranda worked his way into a 2-0 count against Rockies reliever Tyler Kinley. With runners on second and third, one out, and the Rays down two runs, Kinley hung a slider. Aranda uncorked his A swing, launching the ball deep to right field. Off the bat, I thought it looked way gone. It didn’t even go 300 feet:
For the Tampa Bay Rays, it was the fearsome power of nature; for the Athletics, the whims of a greedy doofus. But while the cause may vary, the outcome is the same: Both teams will play all 81 of their home games this season in minor league parks. The A’s will set up shop at Sutter Health Park, also known as the home of the Triple-A River Cats; the Rays’ address is now George M. Steinbrenner (GMS) Field, the erstwhile environs of the Single-A Tampa Tarpons. (The River Cats will share custody, while the Tarpons will move to a nearby backfield.)
This is suboptimal and sort of embarrassing for the league. But it does present a compelling research question: How will these parks play? According to the three-year rolling Statcast park factors, the Oakland Coliseum and Tropicana Field both qualified as pitcher-friendly. The Coliseum ranked as the sixth-most pitcher-friendly park, suppressing offense 3% relative to league average, while Tropicana ranked as the third most, suppressing offense around 8%. Where will Sutter Health and GMS Field settle in?
I started by looking at how each park played in their previous minor league season. Over at Baseball America, Matt Eddy calculated the run-scoring environment for each ballpark in the 11 full-season minor leagues. Eddy found that Sutter Health ranked as the most pitcher-friendly Pacific Coast League park by far in 2024, allowing 31% fewer runs than the average PCL park. GMS Field played closer to neutral compared to its Florida State League peers, but it did significantly boost home runs, particularly to left-handed hitters. Read the rest of this entry »
After wrapping up our position player rankings last week, we turn our attention to the league’s pitchers, starting with the bullpens in the bottom half of the reliever rankings.
It’s impossible to project relievers. The pitchers themselves are random enough, sprouting new pitches or gaining five ticks on their fastball with no prior warning. Pitchers also tend to get injured, especially the ones who go max effort on every pitch. And then there’s the randomness of 60-inning samples, where a fly ball sneaking just past the glove of a leaping outfielder can catapult an ERA from respectable to disastrous. This is all to say that the task of forecasting a bullpen’s performance over the course of a single year is destined to fail.
So I’ll take this introduction as an opportunity to encourage you to not take the order of these rankings too seriously. Less than one-tenth of a win separates some of these teams. There is perhaps just one truly terrible bullpen in the mix; every other team essentially has a mix of proven shutdown guys, solid middle-inning depth, and intriguing wild cards. With that said: To the rankings! Read the rest of this entry »
I’m not much of a YouTube guy or, really, a fan of videos in general. If you send me an Instagram reel, I’m sorry, I will not watch it. But Lance Brozdowski delivers his baseball thoughts in video form, so I am compelled to make an exception. Lance’s posts prodded me to start writing about baseball in the first place; I always learn something when I watch his stuff and tend to agree with all of his analysis.
So I was shocked — shocked! — to hear him express pessimism about Spencer Schwellenbachin a recent video. All through this offseason, I’ve had the opposite thought: There isn’t enough enthusiasm about Schwellenbach’s rookie campaign, during which he posted a 3.29 FIP over 123.2 innings. But Lance wasn’t the only one with a tepid appreciation for the right-hander. Eno Sarris ranked him as his 34th-best starting pitcher; Thomas Nestico had him at no. 36. If I were obliged to make such a list, I might be pushing him some 20 spots higher. I think Schwellenbach’s rookie excellence can be repeated and even improved upon for one key reason: When he delivers the baseball, nobody knows what to expect. Read the rest of this entry »
