Swing decisions are generally evaluated with limited nuance. We consider whether the pitch was in the strike zone (as defined by your data provider of choice) and whether the batter swung. Over the course of hundreds or thousands of pitches, this provides an easy-to-comprehend method of effectively evaluating a player’s approach. With a sufficient sample, these binary classifications give us insight into how players approach their plate appearances relative to their peers, which hitters are better at discerning the strike zone and which are more aggressive.

I have a bone to pick, though: there is often no differentiation between pitches that just miss the defined strike zone versus those that miss by multiple feet, or pitches that just nick the strike zone as opposed to pitches right down the middle. A lot of swing decision analysis is done in the binary, but as many analysts have shown, looking at the gradations in the strike zone can be revealing. Granted, this distinction lacks meaning over many pitches; selective hitters with elite batting eyes will separate from their less fastidious peers with respect to chase rate over time. But in smaller samples, the lack of distinction between pitches and their proximity to the strike zone makes judging a player’s swing decisions difficult.

One method we can use is to group pitches by their probability of being called a strike. Similar to how pitches are evaluated for the purpose of studying catcher framing, I created a general additive model for gauging the probability that a given pitch would be called a strike. My model was trivial (relative to the research I linked above) in that I just considered pitch location and pitch movement; for the purpose of this exercise, I thought that would be enough to get the idea across. The model was trained on 80% of pitches called a ball or strike from the 2020 season, with the remaining 20% used as the test set. For the test set, the model was about 92.5% accurate, in that it correctly predicted whether a pitch was called strike 92.5% of the time.

I applied the model to all pitches from the 2019 and ’20 regular seasons, which yielded the probability of a called strike on every pitch. Pitches with higher probabilities of being a called strike if taken are toward the heart of the zone. Pitches at the edges of the zone have anywhere from a 40–60% chance of being called a strike. And pitches with expected probabilities closer to zero are nowhere near the strike zone.

I binned every pitch in increments of 10% of called strike probability. The following represents the swing rates in each of those bins:

As one would imagine, the league as a whole swings at pitches that have higher called strike probabilities; the closer the pitch is to the heart of the zone, the higher that probability. Break those probabilities down even further, and you can see that the chance of a swing increases steadily with called strike probability.

Swing rates increase rapidly as the called strike probability approaches 0 and 100%. For the more competitive pitches, the changes in swing rate are much smaller. Intuitively, you would expect this relationship to be linear throughout the probability interval; for every 1% increase in called strike probability, the swing rate would also increase by some corresponding percent described by the slope of a line regardless of where you are along this interval. This is not the case.

My hunch is that once a pitch reaches a certain threshold of competitiveness (in terms of challenging the hitter to swing), the swing decision is not as tethered to the chance of the pitch being called a strike. Instead, the choice depends on the pitch type and what the hitter is guessing or picks up out of the pitcher’s hand. Addressing the rapid increase in swing rate on the lower end of the spectrum, I would imagine that many of these pitches are thrown in advantageous counts from the perspective of the pitcher — two-strike counts. While the lack of stigma surrounding strikeouts has been talked about ad nauseam in baseball circles, hitters still do not want to strike out. So if these less competitive pitches are often being thrown with two strikes, the swing rate increases are going to be more sensitive to any marginal change in called strike probability. Break it down by count, and you can see that that’s the case:

For the sharp increase on the higher end of the range, my theory is the same as the other end of the spectrum: Pitches approaching a 100% called strike probability are so enticing to swing at that batters will disregard the count to attack them. Murkier pitches will not really be swung at in 2–0, 3–0 or 3–1 counts, but if the pitch is close to an automatic strike, it must be toward the heart of the plate; a batter who has the green light will want to swing.

For context, league-wide swing rates have oscillated between 45–47% over the past decade. Swing rates on pitches with a called strike probability between 40–60% generally fell in this range in 2019 and ’20. It’s the extreme ends of the spectrum where hitter behavior changes most rapidly. We also saw that the count has a significant effect on the swing rates for any given pitch, especially those that were most and least competitive. So, we know the general league-wide trends and we understand why this is a more nuanced method in evaluating swing decisions. What about at the player level? I found a couple of interesting quirks. When you look at the players who are most aggressive on the pitches that are the most advantageous to swing at (those with a called strike probability of at least 90%), you get a mix of players who we think of as having good plate discipline and those who are more free swingers:

Freddie Freeman, Luke Voit, Brandon Lowe, and Corey Seager are all examples of players we generally understand as having good plate discipline. They lay off pitches that have very little chance of resulting in a called strike and attack pitches that can result in positive outcomes on contact. This list also includes Jeff McNeil, Jay Bruce, and Jorge Alfaro, all of whom swing at pitchers at rates higher than league average no matter the location. This type of strategy can work for a player like McNeill, who has displayed throughout his career he is among the league’s best at making contact. For players like Bruce and Alfaro, this is a recipe for either falling out of the league (in the case of Bruce) or finding more time on the bench as time goes on (in the case of Alfaro). On the other end of the spectrum, the analysis is more cut and dry:

Here we have a list of players who we consider either disciplined or passive. These players do a good job of avoiding swinging at bad pitches, but it seems to be more of a product of just not swinging at all. It could also mean that these players are zeroing in on “their pitches to hit,” and can lead to very good seasons (see: Yasmani Grandal, Mitch Garver, and until this season David Fletcher, Brett Gardner, and Eric Sogard) but passing up good pitches can be problematic without either elite power or contact ability (see: Greg Garcia, Harrison Bader before 2021, and Josh VanMeter). This extreme passivity is a fine line to walk; as you can see after great combined 2019-20 seasons, Fletcher, Gardner, and Sogard have fallen off this season after posting very good lines previously. Fletcher especially is one of the best at putting the bat-head on the baseball, but his passivity may be catching up to him as the league has collected more data on his swing patterns.

Finally, here were the most aggressive and passive swingers on pitches with very little chance of becoming a strike:

Unsurprisingly, batters who avoid swinging at the worst pitches tend to post good results. The other end is a bit of a mixed bag. Tim Anderson has gotten away with what we would consider poor swing decisions because of his demonstrated ability to post high-end BABIPs the past few years, a combination of hitting the ball at angles that result in singles and his foot speed. Javier Báez has posted excellent lines (2020 notwithstanding) by slugging his way to success. Without outlier skills, this sort of approach leads to lackluster performance. Before 2020, José Iglesias was not a good hitter in the majors. Kevin Pillar and Hanser Alberto have mostly posted middling results, and I talked about Alfaro’s issues above.

There is not a one-size-fits-all method of approaching plate appearances. A player’s ability to make contact and his power are the driving forces behind how often he should swing and which pitches he should choose to offer at. This conclusion is nothing revelatory but distinguishing swing decisions based on its chance of being a strike if taken gives additional insight into certain players’ plate discipline profiles. Freddie Freeman or Juan Soto, how swing clearly can track the ball very well and we know they have great discipline. But their plate discipline is different than a player like Yasmani Grandal, who has also displayed discipline throughout his career, though that discipline manifests itself in a much more passive approach. When parsing swing decisions by the quality of a pitch on a granular level, players can get by either through aggression or selectivity. This also shows that free-swingers are free-swingers, no matter the pitch. Baseball players and their skills contain multitudes. When we deal with samples in terms of pitches faced, it helps to further parse the information at hand to get a better understanding of how players struggle or perform well.

Ryan Pepiot is No. 6 on our Los Angeles Dodgers Top Prospects list largely because of his changeup. Baseball America has described the 23-year-old’s best pitch as “devastating [and] plus-plus,’ while our own Eric Longenhagen has likened it to Devin Williams’s Airbender. Per BA, Pepiot has the second-best changeup in the minors, with only Jackson Kowar’s grading out as better.

The Dodgers’ third-round pick in the 2018 draft out of Butler University, Pepiot has made six starts with the Double-A Tulsa Drillers this year and has a 1.64 ERA to go with 33 strikeouts — and just 10 hits allowed — in 22 innings of work. He discussed his signature offering, and touched on the rest of his repertoire, prior to last night’s game.

———

David Laurila: How would you describe your changeup?

Ryan Pepiot: “I’m trying to make it as close to a screwball as possible. A lot of guys cut the spin when they throw their changeups, but the way mine works, I actually spin the ball more than I do my fastball. It’s kind of like how Devin Williams does it, where he spins it close to 3,000 [rpm]. I’m not that high — I’m in the 2,500-2,600 range — but I get arm-side fade and depth. I throw a four-seam circle change, and that allows the spin to look closer to a fastball from a hitter’s perspective. That helps get swings-and-misses, and also takes on pitches that sometimes I wouldn’t get takes on if it was a two-seam changeup and you could see the spin.”

Laurila: It sounds like you don’t back away from the Devin Williams comps you’ve gotten at times.

Pepiot: “No. I see his and I’m like, ‘That’s just gross.’ Like, how do you make something move like that? When I’m out there, I’m trying to do something similar.”

Laurila: What is the story behind your changeup? You don’t just walk onto the mound and start throwing a pitch like that. Read the rest of this entry »

One of the bigger on-field stories of the 2021 season has been which pitchers are using foreign substances, and how much help they’re getting from it. Whether it’s Giovanny Gallegos and hat-gate, Gerrit Cole’s word salad about Spider Tack, or Trevor Bauer’s wildly fluctuating spin rate, what pitchers do to the ball has been a hot topic. Yesterday, the league opened a new chapter in the saga when they released a memo that details a drastically increased enforcement policy, one that promises more suspensions than seemed imaginable only a year ago.

The new rule is draconian and more or less without exception. If a pitcher is caught with foreign substances on the ball or on their person, they’ll be immediately ejected from the game. They’ll also be automatically suspended. The memo, which FanGraphs obtained a copy of, doesn’t specify a suspension length. It does tie the suspensions to the existing rules and past precedent, however, which suggests a 10-game suspension with pay for any violations, a figure the league made explicit in its press release.

“Any foreign substance” is a massive change from the way baseball is currently played. The rule is intended, at least in theory, to crack down on synthetic grip enhancers, such as Spider Tack, that create huge increases in grip strength and spin rate. Pitchers have used lower-potency grip enhancers for years; mixing sunscreen and rosin or dabbing pine tar on the fingertips are both time-tested practices. Read the rest of this entry »

Vladimir Guerrero spent 16 years in the majors, hitting .318 with 449 home runs and nabbing scores of overambitious baserunners with his cannon of an arm. Just a couple years ago, he gave his induction speech in Cooperstown after breezing into the Hall of Fame on his second appearance on the ballot. For a son getting into the same profession, matching those accolades is a tall order, one of Jon Rauchian proportions. But after a so-so start to his major league career, Vladimir Guerrero Jr. is having a breakout season and now threatens to do something Dad never did: win a Triple Crown.

That the younger Guerrero is quite adept at hitting a baseball shouldn’t shock anyone, though his first two stints in the majors were admittedly more middling than magical. But hype is difficult, and I suspect that if he played under a nom de guerre rather than a nom de Guerrero, people would likely have been far more patient before starting to worry about him. As I wrote about Guerrero in my preseason breakout picks:

Perhaps not the gutsiest call, but it feels to me like people have soured way too much on Vladito. A 112 wRC+ won’t win any Silver Sluggers, but we have to remember he was just 21 last season. Let’s imagine that Guerrero Jr. wasn’t part of the imperial-Vlad bloodline and was just a guy in Triple-A in 2020 (in an alternate universe where the minor league season existed). If we translate Guerrero’s actual major league performance into a Triple-A Buffalo line, ZiPS estimates that he would’ve been hitting .288/.370/.526 as a 21-year-old in the International League. Would anyone be disappointed with this line? There would be cries of Free Vlad! echoing through the streets by June. I think players like Juan Soto and Fernando Tatis Jr. have spoiled us for normal awesome prospects.

While he was one of my favorite breakout picks, I certainly can’t claim to have seen a breakout on this particular level. If we look back at the preseason projections, neither could ZiPS:

Now, he hasn’t yet completed 2021 with a wRC+ of 206, but if he did, that’s in 99th percentile territory. I’ve been working on calibrating this model since the start of the season, and projected right now, his 90th percentile wRC+ gets a bump to 163, but 206 still would have been seen as a one-in-50 shot to happen.

As of Tuesday morning, Guerrero leads the American League in batting average, home runs, and RBI, baseball’s Triple Crown components. His sterling performance has been enough for a wRC+ bump of an impressive 27 points since March in ZiPS’ estimate of his current level of ability. At this point, it’s hard to argue his ceiling has been raised; the main question is how high. In the updated projections, which combine year-to-date with the rest-of-season projections, ZiPS has Guerrero leading the league in home runs and RBI and finishing second in batting average behind Michael Brantley. Steamer has Guerrero leading in all three categories.

Even if the stats were reset to zero, Vladito’s projections have improved to the point that he’d have a fighting chance to lead in the three stats, and be in the top 10 in each.

What this doesn’t tell us is the probability that Vlad does, in fact, win the Triple Crown. For that, I used the ZiPS season simulation and projected the rest of 2021 a million times for the American League, then added to the stats already in the books, counting — by computer, not by hand, of course– how many times each player led the league in the Triple Crown categories.

Injuries have been a red flag for Brantley, but he’s been healthy enough to qualify for the batting title in three consecutive seasons after missing more than 200 games in 2016 and ’17 combined. Assuming perfect health, ZiPS would give him about a 43% chance of taking the batting title, but with him already having missed time with a hamstring injury, he has a smaller margin of error in getting the required plate appearances. ZiPS sees Vlad at the back of the top 10 in rest-of-season batting average, but he’s got a 23-point cushion over the non-Brantley candidates. Also providing an assist is that two of the bigger threats, Mike Trout and Luis Arraez, are almost certainly going to fall short of 3.1 plate appearances per game (or lose too much BA if they fall just short in PA).

ZiPS still sees Matt Olson and Giancarlo Stanton as better home run hitters, but the four-homer edge to date is enough to leave Vlad the favorite over either. The computer projects him with a 44% shot to beat his dad’s career-high of 44; it surprises me too, but Vlad Sr. never led the league (or finished second) in any Triple Crown stat. The projections give him a 28% chance to pass the 50-homer threshold.

José Abreu isn’t repeating his 2020 season, but he’s still a player who should hit for power, even in a relative down season. As importantly, Abreu hits third or fourth in a White Sox lineup that’s been surprisingly potent for a team that’s lost Eloy Jiménez and Luis Robert. Nobody has more plate appearances with runners on base this season than Abreu. But the Jays are no slouches, and as with the other categories, Guerrero has the lead right now.

If you wanted to be lazy, you’d multiply Vlad’s probability of leading each category together and get 2.6%, decent odds of getting into the record books. That, of course, is something you cannot actually do since these aren’t independent variables. The hundred games of baseball that leave Guerrero with the home run title also leave him with the RBI title most of the time. Batting average isn’t as highly correlated with the others, but if Guerrero hits .340, well, many of those hits will be homers and/or drive in runners. All told, ZiPS gives him a 19.1% chance of winning the Triple Crown. Not a bad shot at something that’s been done once in the last half-century.

Leading all of baseball in the Triple Crown categories — the Triple Crown Magnifique, as I like to call it — is a trickier challenge. That one hasn’t been done since Mickey Mantle in 1956, and Vlad has tough competition in this one. Fighting against Fernando Tatis Jr. and Ronald Acuña Jr. in a battle for junior supremacy drops his chances from 19.1% to well under 1% (0.2%).

Whether he wins the Triple Crown or not, it appears the Vladimir Guerrero Jr. era is in full swing. I don’t have kids, but I’m at least of the belief that most parents hope to see their children exceed their accomplishments. Vladito has a long way to go, but 2021 looks like the start of a run that may end with him achieving just that.

Lyon Richardson remains raw with a ton of potential. Ranked sixth on our Cincinnati Reds Top Prospects list, the 21-year-old right-hander has a 5.13 ERA in seven starts for High-A Dayton, but he also has a pair of a high-octane heaters, a plus changeup, and a hard curveball that gets side-to-side movement. What he lacks more than anything is experience on the mound. Primarily a position player as a Florida prep, Richardson didn’t become a starter until his senior year at Jensen Beach High School. It was then that he began turning heads. Enamored with his athleticism and explosive velocity, the Reds selected him with the 47th-overall pick of the 2018 draft.

Richardson discussed his arsenal, and the learning curve that goes along with it, late last week.

———

David Laurila: Describe yourself as a pitcher.

Lyon Richardson: “I haven’t been pitching for very long. I just try to learn as much as I can, and be as aggressive as I can. At this point, I don’t really have the ability to give in, if that makes any sense. So really, I just try to be as aggressive as possible and push the hitter.”

Laurila: Would you say you’re more of a “stuff guy” right now?

Richardson: “For the most part, in the history of me pitching, I’m a thrower. Historically, I’m a position player, so all I really knew was to throw hard. I’m trying to be more of a stuff guy, but it’s in production. It’s definitely a production.”

Laurila: By and large, you’re trying to be a stuff guy and learning to “pitch” at the same time?

Richardson: “Correct. So, my velocity is definitely up — especially over the past year — and being able to control the pitches with that velocity is definitely a big thing. In 2019, I think my average fastball was 89 to 92 [mph] — something like that. Out of high school, I was anywhere from 95 to 98. This year, it’s back up to right around high school range. I was up to 98 in spring training, and I’ve been up to 97 a bunch so far this season.” Read the rest of this entry »

For over two decades, Baseball Reference has served as the most direct conduit to the game’s statistical history, going beyond Major League Baseball’s gatekeeping to provide access to a fuller swath of leagues and teams dating back to the inception of the National Association in 1871. On Tuesday, the site officially launched its expanded coverage of the Negro Leagues and historical Black major league players, a monumental effort incorporating data previously available only via the Seamheads Negro League Database and accompanying it with commissioned articles by experts on Negro Leagues baseball to help place that data in perspective.

“With this change, we now present these Black major leagues as the equals of the American and National Leagues,” said Sports Reference President Sean Forman via Zoom press conference on Monday. “We have had Negro Leagues baseball stats on Baseball Reference for at least 10 years now, but we treated them as less than the statistics of the white major leagues. We will now treat them as the major leagues that they are.”

“Our decision to fix this omission is just a tiny part of the story,” continued Forman. “The main story here is the work of hundreds of researchers, activists, players, and families who did the research, made their arguments, and would not let the memories of these players and leagues fade away.”

For Monday’s event, Forman was joined by both Sean Gibson and Larry Lester as representatives of “the groups most central to this story, the players and their families and the researchers who told their stories.” Gibson is the great-grandson of Hall of Fame slugger Josh Gibson and the executive director of the Josh Gibson Foundation, which provides athletic, academic, and mentoring programs for children in the Pittsburgh area. Lester is an award-winning researcher who co-founded the Negro Leagues Baseball Museum; who has worked extensively with the National Baseball Hall of Fame and Museum in its research into Black baseball; who helped compile the Seamheads database; and who for over 25 years has chaired SABR’s Negro Leagues Committee. Read the rest of this entry »

I like the Marlins pitching staff. There’s a certain charm to a rotation that mostly consists of farm-grown talent, and it’s a powerhouse, too. Sandy Alcantara and Trevor Rogers have become two of the league’s more reliable starters by virtue of their electric stuff, with room for further growth. The bullpen is home to a diverse group of relievers whose idiosyncrasies are so irresistible that we’ve written about a member of Miami’s relief corps not once, but twice – and it’s not even the offseason! Collectively, the Marlins ‘pen has accrued 2.7 WAR, good for fourth-best in the majors.

Rarely is there one reason for success like this. In all likelihood, the Marlins have excelled at pitching because they just happen to roster good pitchers. With teams increasingly tailoring plans to the needs of individual pitchers, team-wide dogmas and philosophies are harder to find. So what follows isn’t an explanation. Rather, it’s a series of observations I find noteworthy. Up first, here’s a graph showing each team’s average vertical break on its four-seam fastball (abbreviated as “fastball” from here on):

Though the gap between first and last is only a couple of inches of movement, we can still glean certain teams’ preferences. For example, teams like the Dodgers, White Sox, and Yankees have a predilection for fastballs that generate ample ride. You know the drill – throw them up in the zone and chances are hitters will swing and miss. It’s a tried and true approach. Read the rest of this entry »

Jacob deGrom is on another planet right now. You don’t need me to tell you this, but it’s fun to just marvel at his stats. Through 10 starts, deGrom has a 0.56 ERA, a 46% strikeout rate, and a 4% walk rate. He’s produced 3.7 WAR, which is nearly a half-win better than the next-best pitcher, Corbin Burnes, who has “merely” put up 3.3.

deGrom is quite possibly in the midst of one of the best pitching seasons in baseball history, particularly on a per-inning basis. Pedro Martinez’s 1999 campaign currently holds the single-season pitching WAR record at 11.6, and though deGrom almost certainly won’t hit that mark, he’d blow it away if he pitched the same number of innings at his current rate. Give deGrom Martinez’s 213.1 innings, and at this pace, he’d put up 12.3 WAR. Say what you will about injuries and starting pitching workloads in this era, but that’s just a primer on the level of dominance deGrom has reached so far in 2021.

So if you’re a hitter stepping in against deGrom, how in the world do you get a hit off this guy? Batters are slashing just .121/.152/.220 against him, good for a .163 wOBA allowed. That’s the best mark among the 294 pitchers with at least 100 batters faced this season, and deGrom has more than doubled that threshold (223 TBF). If you’re hitting against deGrom, you’re lucky if you just put the ball in play, let alone get on base.

Is there an alternative strategy that works here? deGrom is raking up all of these strikeouts — without allowing virtually any walks — while boasting the seventh-lowest Zone% in baseball. Hitters are flailing against pitches that aren’t even strikes anyway: 60.5% of the time, deGrom is throwing the hitter a ball. If you’re in a two-strike count, he’ll throw you a ball 64.5% of the time, putting him in the 91st percentile in O-Zone%. Read the rest of this entry »

After last week’s games, we’re around 40% of the way through the season. The halfway mark is quickly approaching, with the All-Star game soon after that. The form of the playoff races is slowly taking shape. And with few exceptions, too many of the teams on the bubble of contention just aren’t making any headway in the standings. There’s still plenty of season left to play, but the trade deadline decision-making point for many of these teams is coming sooner rather than later.

A quick refresher: my approach takes the three most important components of a team — their offense (wRC+), and their starting rotation and bullpen (50%/50% FIP- and RA9-) — and combines them to create an overall team quality metric. I add in a factor for “luck” — adjusting based on a team’s expected win-loss record — to produce a power ranking.

Despite neither team moving at all in the rankings, this tier saw the biggest changes this week. Both the White Sox and the Rays continued to pull away from the rest of the field in the American League, with each team losing just once last week. These two powerhouses are set to play three games in Chicago, which should be a fantastic preview of a potential AL Championship Series.

Chicago and Tampa Bay have scored the exact same number of runs this season but the White Sox have a decided advantage when it comes to their starting rotation. If the season ended today, their starters would have the third lowest park- and league-adjusted ERA of any team since the mound was lowered in 1969. And all this despite some significant struggles on the part of their staff ace, Lucas Giolito. They’ve thrived despite some extremely unfortunate injuries — Nick Madrigal is the latest victim — because they’ve built the best run prevention unit in the American League. Read the rest of this entry »

Here at FanGraphs, we’re always looking for an excuse to paraphrase Tolstoy, so let me introduce you to a principle I’ve recently noticed about sacrifice bunts. Successful sacrifice bunts are all alike (and boring). Every unsuccessful sacrifice bunt is unsuccessful in its own way. Let’s talk about the worst sacrifice bunts of the year and explore the myriad “own ways” you can fail.

First, some ground rules. I’m looking at every bunt through June 9; that’s the last day I pulled data for. (Don’t you worry: I don’t need an excuse to write about future bad bunts later this year.) I’m ranking them based on win probability added. I’m considering the results of the play, not just the decision to call for a bunt in the first place. That might be more theoretically useful, but it’s a lot less fun; we want to watch bunt train wrecks, not debate the finer points of ex-ante strategy. The worst bunting decision of the year is arguable, and dependent on many factors which can be hard to pin down. The worst result? It’s pretty clear, as you’ll see.
Read the rest of this entry »