On August 18 in Colorado, Ha-Seong Kim led off first base, then dived back to beat a pickoff attempt. He tore the labrum in his right shoulder, and that was the last time we saw him play in 2024. After a failed rehab attempt, Kim underwent surgery in October, and he won’t be ready to play again until sometime between April and June. Just as uncertain: Where exactly Kim will be suiting up when he returns. There’s no doubt about his skill. Over the past four years, Kim has spent time at second, short, and third, and neither DRS nor FRV has ever rated him as below average at any of those spots. He needed a year to adjust on offense after arriving from the KBO in 2021, but over the past three seasons, he’s run a 106 wRC+. That ranks 13th among shortstops, and over the same period, his 10.5 WAR ranks 11th.

Kim entered free agency after both he and the Padres declined their ends of a mutual option, and he came in at ninth on our Top 50 Free Agents. According to the projections, he’ll command a four- or five-year deal with an AAV in the neighborhood of $19 million. However, the shoulder injury could cost him as much as half of the 2025 season, and it makes for a tough needle to thread. He’s got to sign with a team that needs a solid infielder, but not badly enough to need one right away. Moreover, a shoulder injury is especially scary for Kim, whose arm strength is an important part of his overall value and who already possesses below-average power at the plate. For that reason, it wouldn’t be surprising to see Kim get a pillow contract: Ben Clemens proposed two years with an opt-out. Back in November, Mark Feinsand reported that Kim had generated “lots of interest,” and wrote about the possibility that he’d be among the first free agents off the board. However, it’s now late January, and if you cruise through our Depth Charts, you’ll notice that there just don’t seem to be many good landing spots for Kim. Let us begin our litanies. Read the rest of this entry »

The following article is part of Jay Jaffe’s ongoing look at the candidates on the BBWAA 2025 Hall of Fame ballot. For a detailed introduction to this year’s ballot, and other candidates in the series, use the tool above; an introduction to JAWS can be found here. For a tentative schedule, see here. All WAR figures refer to the Baseball Reference version unless otherwise indicated.

Adam Jones was Mr. Baltimore. Though he was born in San Diego and began his major league career in Seattle, Jones took to Baltimore upon being traded to the Orioles in 2008. On the field, he set an example for younger teammates during lean years, and his combination of power, speed, and graceful defense eventually helped the team end an epic streak of futility. He served as a starter on the Orioles’ first three playoff teams in this millennium, winning four Gold Gloves and making five All-Star teams. Off the field, Jones invested in the city, annually donating a significant chunk of his salary to the local Boys & Girls Club and other charitable endeavors. He emerged as a civic icon, a Black athlete who could relate to the hardships experienced by the city’s Black population, and one who wasn’t afraid to speak out regarding the injustices he saw both locally and nationally.

Jones’ national prominence reached its zenith in 2017 when he made a memorable, iconic catch to rob Manny Machado of a home run while playing center field during the World Baseball Classic — a key moment in helping Team USA win the tournament for the only time thus far. Read the rest of this entry »

The following article is part of Jay Jaffe’s ongoing look at the candidates on the BBWAA 2025 Hall of Fame ballot. For a detailed introduction to this year’s ballot, and other candidates in the series, use the tool above; an introduction to JAWS can be found here. For a tentative schedule, see here. All WAR figures refer to the Baseball Reference version unless otherwise indicated.

Fernando Rodney is a man of many hats, most of them slightly askew. Over the course of a 17-year major league career, the Dominican-born reliever showed off his signature style while pitching for 11 different teams, and that’s not even counting his minor league, independent, winter league, or international stops. During his time, he notched 327 saves (19th all-time), made three All-Star teams, and pitched in two World Series, earning a ring with the 2019 Washington Nationals. In the process, he gave the hearts of his managers plenty of workouts as his command came and went, forcing him to work his way out of jams. But when it all came together for Rodney — as it did in 2012, when he posted a microscopic 0.60 ERA while saving 48 games for the Rays — he was a sight to behold.

Rodney’s crooked hat was just one of his famous quirks. He also shot an imaginary arrow into the sky after closing games, most famously upon recording the final out for the Dominican Republic in the 2013 World Baseball Classic championship game.

Read the rest of this entry »

This year I had the honor of filling out a Hall of Fame ballot for the fifth time, and as was the case with the previous four, I‘m endeavoring to explain my reasoning. This is something I feel every voter should do. Casting a ballot is a privilege that should demand not only due diligence, but also transparency.

Let’s cut to the chase.

Noteworthy among my 2025 selections is that the holdovers differ somewhat from previous ballots. My most recent Sunday Notes column — I missed last week’s due to a health issue — suggested a few of those changes. As I explained on December 22, my previous ballots all included Manny Ramirez and Alex Rodriguez, but I was seriously considering dropping them and instead voting for two of Félix Hernández, Dustin Pedroia, and David Wright. I did just that. Following no small amount of deliberation, I adopted my colleague Jay Jaffe’s stance that Manny’s and A-Rod’s being suspended after PED rules were put into place is a meaningful distinction. With neither erstwhile slugger having a realistic chance of ever being elected by the BBWAA — another factor in my decision — a strategic change seemed in order.

More on that in a moment. Read the rest of this entry »

Rickey Henderson had something to offer everyone. He was a Bay Area icon who spent more than half his career wearing the green and gold of the Oakland Athletics, yet he was traded away twice, and spent time with eight other teams scattered from Boston to San Diego, all of them viewing him as the missing piece in their quest for a playoff spot. For fans of a throwback version of baseball that emphasized speed and stolen bases, “The Man of Steal” put up numbers that eclipsed the single-season and career records of Lou Brock and Ty Cobb. To those who viewed baseball through the new-fangled lens of sabermetrics, he was the platonic ideal of a leadoff hitter, an on-base machine who developed considerable power. To critics — including some opponents — he was a showboat as well as a malcontent who complained about being underpaid and wouldn’t take the field due to minor injuries. To admirers, he was baseball’s most electrifying player, a fierce competitor, flamboyant entertainer, and inner-circle Hall of Famer. After a 25-year major league career full of broken records (not to mention the fourth-highest total of games played, ahem), Henderson spent his age-45 and -46 seasons wowing fans in independent leagues, hoping for one last shot at the majors.

It never came, but Henderson’s résumé could have hardly been more complete. A 10-time All-Star, two-time world champion, an MVP and Gold Glove winner, he collected 3,055 hits and set the career records for stolen bases (1,406), runs scored (2,295), and walks (2,190); the last was eclipsed by Barry Bonds three years later, though Henderson still has more unintentional walks (2,129). He also holds the single-season record for stolen bases (130), as well as the single-season and career records for caught stealing (42 and 335, respectively).

“If you could split him in two, you’d have two Hall of Famers. The greatest base stealer of all time, the greatest power/speed combination of all time (except maybe Barry Bonds), the greatest leadoff man of all time,” wrote Bill James for The New Bill James Historical Baseball Abstract in 2001. “Without exaggerating one inch, you could find fifty Hall of Famers who, all taken together, don’t own as many records, and as many important records, as Rickey Henderson.” Read the rest of this entry »

Right after FanGraphs published my piece on the Kirby Index, the metric’s namesake lost his touch. George Kirby’s trademark command — so reliable that I felt comfortable naming a statistic after him — fell off a cliff. While the walk rate remained under control, the home run rate spiked; he allowed seven home runs in May, all on pitches where he missed his target by a significant margin.

Watching the namesake of my new metric turn mediocre immediately following publication was among the many humbling experiences of publishing this story. Nevertheless, I wanted to revisit the piece. For one, it’s December. And writing the story led me down a fascinating rabbit hole: While I learned that the Kirby Index has its flaws, I also learned a ton about contemporary efforts to quantify pitcher command.

But first, what is the Kirby Index? I found that release angles, in concert with release height and width, almost perfectly predicted the location of a pitch. If these two variables told you almost everything about the location of a pitch, then a measurement of their variation for individual pitchers could theoretically provide novel information about pitcher command.

This got a few people mad on Twitter, including baseball’s eminent physicist Alan Nathan and Greg Rybarczyk, the creator of the “Hit Tracker” and a former member of the Red Sox front office. These two — particularly Rybarczyk — took issue with my use of machine learning to make these predictions, arguing that my use of machine learning suggested I didn’t understand the actual mechanics of why a pitch goes where it goes.

“You’re spot on, Alan,” wrote Rybarczyk. “The amazement that trajectory and launch parameters are strongly associated with where the ball ends up can only come from people who see tracking data as columns of digits rather than measurements of reality that reflect the underlying physics.”

While the tone was a bit much, Rybarczyk had a point. My “amazement” would have been tempered with a more thorough understanding of how Statcast calculates the location where a pitch crosses home plate. After publication, I learned that the nine-parameter fit explains why pitch location could be so powerfully predicted by release angles.

The location of a pitch is derived from the initial velocity, initial release point, and initial acceleration of the pitch in three dimensions. (These are the nine parameters.) Release angles are calculated using initial velocity and initial release point. Because the location of the pitch and the release angle are both derived from the 9P fit, it makes sense that they’d be almost perfectly correlated.

This led to a reasonable critique: If release angles are location information in a different form, why not just apply the same technique of measuring variation on the pitch locations themselves? This is a fair question. But using locations would have undermined the conclusion of that Kirby Index piece — that biomechanical data like release angles could improve the precision of command measurements.

Teams, with their access to KinaTrax data, could create their own version of the Kirby Index, not with implied release angles derived from the nine-parameter fit, but with the position of wrists and arms captured at the moment of release. The Kirby Index piece wasn’t just about creating a new way to measure command; I wanted it to point toward one specific way that the new data revolution in baseball would unfold.

But enough about that. It’s time for the leaderboards. I removed all pitchers with fewer than 500 fastballs. Here are the top 20 in the Kirby Index for the 2024 season:

And here are the bottom 20:

A few takeaways for me: First, I am so grateful Kirby got it together and finished in the top three. Death, taxes, and George Kirby throwing fastballs where he wants. Second, the top and bottom of the leaderboards are satisfying. Cody Bradford throws 89 and lives off his elite command, and Joe Boyle — well, there’s a reason the A’s threw him in as a piece in the Jeffrey Springs trade despite his otherworldly stuff. Third, there are guys on the laggard list — Seth Lugo and Miles Mikolas, in particular — who look out of place.

Mikolas lingered around the bottom of the leaderboards all year, which I found curious. Mikolas, after all, averages just 93 mph on his four-seam fastball; one would imagine such a guy would need to have elite command to remain a viable major league starter, and that league-worst command effectively would be a death sentence. Confusing this further, Mikolas avoided walks better than almost anyone.

Why Mikolas ranked so poorly in the Kirby Index while walking so few hitters could probably be the subject of its own article, but for the purposes of this story, it’s probably enough to say that the Kirby Index misses some things.

An example: Mikolas ranked second among all pitchers in arm angle variation on four-seam fastballs, suggesting that Mikolas is intentionally altering his arm angle from pitch to pitch, likely depending on whether the hitter is left-handed or right-handed. This is just one reason why someone might rank low in the Kirby Index. Another, as I mentioned in the original article, is that a pitcher like Lugo might be aiming at so many different targets that it fools a metric like the Kirby Index.

So: The Kirby Index was a fun exercise, but there are some flaws. What are the alternatives to measuring pitcher command?

Location+

Location+ is the industry standard. The FanGraphs Sabermetric library (an incredible resource, it must be said) does a great job of describing that metric, so I’d encourage you to click this hyperlink for the full description. The short version: Run values are assigned to each location and each pitch type based on the count. Each pitch is graded on the stuff-neutral locations.

Implied location value

Nobody seems particularly satisfied with Location+, including the creators of Location+ themselves. Because each count state and each pitch type uses its own run value map to distribute run value grades, it takes a super long time for the statistic to stabilize, upward of hundreds of pitches. It also isn’t particularly sticky from year to year.

The newest version of Location+, which will debut sometime in the near future, will use a similar logic to PitchProfiler’s command model. Essentially, PitchProfiler calculates a Stuff+ and a Pitching+ for each pitcher, which are set on a run value scale. By subtracting the Stuff+ run value from the Pitching+ run value, the model backs into the value a pitcher gets from their command alone.

Blobs

Whether it’s measuring the standard deviation of release angle proxies or the actual locations of the pitches themselves, this method can be defined as the “blob” method, assessing the cluster tightness of the chosen variable.

Max Bay, now a senior quantitative analyst with the Dodgers, advanced the Kirby Index method by measuring release angle “confidence ellipses,” allowing for a more elegant unification of the vertical and horizontal release angle components.

Miss distance

The central concern with the Kirby Index and all the blob methods, as I stated at the time, is the single target assumption. Ideally, instead of looking at how closely all pitchers are clustered around a single point, each pitch would be evaluated based on how close it finished to the actual target.

But targets are hard to come by. SportsVision started tracking these targets in the mid-2010s, as Eno Sarris outlined in his piece on the state of command research in 2018. These days, Driveline Baseball measures this working alongside Inside Edge. Inside Edge deploys human beings to manually tag the target location for every single pitch. With these data in hand, Driveline can do a couple of things. First, they created a Command+ model, modifying the mean miss distances by accounting for the difficulty of the target and the shape of a pitch.

Using intended zone data, Driveline also shows pitchers where exactly they should aim to account for their miss tendencies. I’m told they will be producing this methodology in a public post soon.

Catcher Targets (Computer Vision)

In a perfect world, computers would replace human beings — wait, let me try that sentence again. It is expensive and time-intensive to manually track targets through video, and so for good reason, miss target data belong to those who are willing to pay the price. Computer vision techniques present the potential to produce the data cheaply and (therefore) democratically.

Carlos Marcano and Dylan Drummey introduced their BaseballCV project in September. (Drummey was hired by the Cubs shortly thereafter.) Joseph Dattoli, the director of player development at the University of Missouri, offered a contribution to the project by demonstrating how computer vision could be used to tag catcher targets. The only limitation, Joseph pointed out, is the computing power required to comb through video of every single pitch.

There are some potential problems with any command measurement dependent on target tracking. Targets aren’t always real targets, more like cues for the pitcher to throw toward that general direction. But Joseph gets around this concern by tracking the catcher’s glove as well as his center of mass, which is less susceptible to these sorts of dekes. Still, there’s a way to go before this method scales into a form where daily leaderboards are accessible.

The Powers method

Absent a raft of public information about actual pitcher targets, there instead can be an effort to simulate them. In their 2023 presentation, “Pitch trajectory density estimation for predicting future outcomes,” Rice professor Scott Powers and his co-author Vicente Iglesias proposed a method to account for the random variation in pitch trajectories, in the process offering a framework for simulating something like a target. (I will likely butcher his methods if I try to summarize them, so I’d encourage you to watch the full presentation if you’re interested.)

The Powers method was modified by Stephen Sutton-Brown at Baseball Prospectus, who used Blake Snell as an example of the way these targeting models can be applied at scale to assess individual pitchers. First, Sutton-Brown fit a model that created a global target for each pitch type, adjusting for the count and handedness of each batter. Then, for each pitcher, this global target was tweaked to account for that pitcher’s tendencies. Using these simulated targets, he calculated their average miss distance, allowing for a separation of the run value of a pitcher’s targets from the run value of their command ability.

“Nothing”

On Twitter, I asked Lance Brozdowski what he saw as the gold standard command metric. He answered “Nothing,” which sums up the problem well. This is a challenging question, and all the existing methods have their flaws.

There are ways that the Kirby Index could be improved, but as far as I can tell, the best way forward for public command metrics is some sort of combination of the final two methods, with active monitoring of the computer vision advancements to see if consistent targets can be established.

But one would imagine the story is completely different on the team side. By marrying the KinaTrax data with miss distance information, these methods could potentially be combined to make some sort of super metric, one that I imagine gets pretty close to measuring the true command ability of major league pitchers. (In a video from Wednesday, Brozdowski reported on some of the potential of these data for measuring and improving command, as well as their limitations.) The public might not be quite there, but as far as I can tell, we’re not that far off.

Editor’s Note: This story has been updated to include Vicente Iglesias as a co-author on the 2023 presentation, “Pitch trajectory density estimation for predicting future outcomes.”

The following article is part of Jay Jaffe’s ongoing look at the candidates on the BBWAA 2025 Hall of Fame ballot. For a detailed introduction to this year’s ballot, and other candidates in the series, use the tool above; an introduction to JAWS can be found here. For a tentative schedule and a chance to fill out a Hall of Fame ballot for our crowdsourcing project, see here. All WAR figures refer to the Baseball-Reference version unless otherwise indicated.

Before he’d ever thrown a major league pitch, cracked a prospect list, or reached legal adult status, Félix Hernández had a nickname: King Felix. Dubbed as such by U.S.S. Mariner blogger Jason Michael Barker Dave Cameron on July 17, 2003, when he was just a 17-year-old in the Low-A Northwest League, he was already overpowering much older hitters. Still a teen when he reached the majors, he quickly came to represent the hopes and dreams of a franchise that had fallen short of a World Series despite four playoffs appearances from 1995–2001; parted with superstars Randy Johnson, Ken Griffey Jr., and Alex Rodriguez along the way; and capped that run with a record-setting 116 wins but a premature exit in the ALCS.

Though slow to embrace the royal moniker, Hernández grew into it. His dazzling combination of an electrifying, darting sinker, a knee-buckling curve, and a signature hard changeup propelled him to a Cy Young Award, two ERA titles, six All-Star appearances, and a perfect game. From 2009–14, he was the best pitcher in the American League by ERA, FIP, strikeouts, and WAR, parlaying that into a contract commensurate that made him the game’s highest-paid pitcher. Unfortunately, a heavy workload — more innings than any pitcher 23 or younger since Dwight Gooden two decades earlier — sapped the sizzle from his fastball, with injuries and a cavalier approach to conditioning taking their toll as well. The Mariners struggled to surround him with a quality roster, and changed managers and pitching coaches every couple of years. The team didn’t reach the playoffs once during Hernández’s career, finishing above .500 just five times, with a pair of second-place showings in the AL West as good as it got. Read the rest of this entry »

When addressing his team’s acquisition of Garrett Crochet at the Winter Meetings, Craig Breslow said that the 25-year-old southpaw’s relationship with the Red Sox’ analytics group will be important, so that he “can continue to understand how he can get the best out of his stuff.” I subsequently asked Boston’s Chief Baseball Officer if, based on their pre-trade homework, they have identified any specific adjustments Crochet might want to make, or if they plan to mostly just let him keep doing what he does.

“I think the answer is probably both,” replied Breslow. “Right? We want to lean into what he does particularly well, and he does a lot of things really, really well. You look at the strikeouts, and especially the strikeouts relative to the walks; that’s a pretty good underpinning for a really successful starting pitcher. Once we have a chance to get to know him, have conversations with him, we’ll lean on [pitching coach Andrew Bailey] and the rest of the group. But it’s probably not fair to talk about what adjustments we might make before we’ve had a chance to have that conversation with him.”

Crochet is looking forward to the conversation. He expects it to take place in the coming week, and he’ll go into it with thoughts he’s been formulating since last summer. When I talked to Crochet in late August, he spoke of usage percentages and how he’d begun tinkering with a sinker. I reminded him of that earlier exchange when he met with the Boston media over Zoom on Friday, then proceeded to ask about his forthcoming discussions with the Red Sox pitching department. Read the rest of this entry »

The following article is part of Jay Jaffe’s ongoing look at the candidates on the BBWAA 2025 Hall of Fame ballot. For a detailed introduction to this year’s ballot, and other candidates in the series, use the tool above; an introduction to JAWS can be found here. For a tentative schedule and a chance to fill out a Hall of Fame ballot for our crowdsourcing project, see here. All WAR figures refer to the Baseball-Reference version unless otherwise indicated.

The fourth and final multi-candidate pairing of this series is by far the heaviest, covering two candidates who have both been connected to multiple incidents of domestic violence. Read the rest of this entry »

Colt Emerson has a bright future, and he is approaching it with a stay-true-to-yourself mindset. Exactly how much his identity will evolve is the question. Seventeen months removed from being selected 22nd overall in the 2023 draft by the Seattle Mariners out of New Concord, Ohio’s John Glenn High School, the left-handed-hitting shortstop is just 19 years old, with all of 94 professional games under his belt. He has plenty of room to grow, with his below-average raw power being part of that equation.

Emerson recognizes that what he is today isn’t necessarily what he’ll be in the future. At the same time, he doesn’t anticipate changing too much.

“I think I have a good feel for the type of player I am,” the 6-foot-1, 195-pound infielder told me during the Arizona Fall League season, where he slashed a lusty .370/.436/.547. “But I’m also not physically mature yet. I have more strength to put on, and as I keep growing into it, hitting the same way is going to be crucial for me. Getting stronger and being able to put balls over the fence more easily doesn’t mean that I need to try to hit more home runs. They’re going to come, just doing what I do.”

What Emerson currently does is hit line drives with a swing that our lead prospect analyst Eric Longenhagen has described as “aesthetically pleasing.” Generated by “lightning quick hands,“ it produced a .263/.393/.376 with for home runs and a 119 wRC+ over 332 plate appearances between Low-A Modesto and High-A Everett. One of the youngest players at each level, he missed time in April with an oblique issue, and in mid-season he was out for a month-plus due to a fractured foot. Read the rest of this entry »