Last week, I looked into the strange fact that starter usage hasn’t declined as precipitously as it first seemed over the past half decade. It’s downright strange that pitchers are throwing nearly as many pitches per start as they did in 2019, because it sure doesn’t feel that way. It’s even stranger that the average start length has declined by a mere half inning since 2008; I’m still scratching my head about that one even though I’m the one who collected the evidence.

One potential answer stood out to me: maybe I was just measuring the wrong thing. Meg Rowley formulated it a bit better when we discussed the article: Maybe by capturing all the pitchers in baseball, I was missing the change in workloads shouldered by top starters. In other words, no one remembers the pitcher who made the 200th-most starts (Xzavion Curry in 2023, Ryan Tucker in 2008), and the usage patterns of back-end starters don’t leave much of an impression in our minds. We care about the horses, the top guys who we see year after year.

Time for a new measurement, then. I took the same cutoff points from last week’s study, which serves to control for early-season workloads. But I further limited the data this time. I first took the 100 pitchers who had thrown the most innings in each year and called them “established starters” for the next year. Then I redid my look at pitch counts per start and innings pitched per start, but only for top pitchers in each year. Read the rest of this entry »

In the modern game, pinch-hitting is seen as something of a lost art. This likely started with teams prioritizing roster spots for extra bullpen arms over spare position players. With that came a heavier emphasis on positional flexibility off the bench, rather than plus contact skills (think Ross Gload) or a big bopping bat (à la Matt Stairs). As an angry Facebook commenter might tell you, it’s one more way that sabermetrics has ruined America’s pastime. Yet, the numbers bear it out; the best arm is often a fresh arm, while conversely, fresh bats off the bench tend to perform significantly worse than their counterparts in the starting lineup. Ahead of the 2020 season, Ben Clemens found that the pinch-hitting penalty, first theorized in 2006, still held 14 years later. Contemplating Ben’s findings, Patrick Dubuque of Baseball Prospectus penned a line that stuck deep in my brain: “Pinch-hitters are just difficult to justify, except when they’re mandatory.”

Pinch-hitters were mandatory far less often in 2020 after the universal DH came into play. However, the age of the universal DH is also the age of expanded rosters and pitcher limits, and those new roster rules may just have saved the pinch-hitter from a slow demise. Pinch-hitters are rarely mandatory anymore, but they haven’t disappeared as much as you might think. Read the rest of this entry »

Release angles comprise the vertical and horizontal angles at which a pitcher releases a pitch. They are the natural counterpart to approach angles, except they capture the initial angle of a pitch’s trajectory rather than its final angle upon crossing home plate. Release angles can tell us a lot — namely, where a pitch is headed (or, at least, intended to go). However, we already have plenty of data to describe a pitch’s flight path. We have its short-form movement (i.e., total inches of break), as well as its acceleration and velocity vectors in all three dimensions, not to mention its final location coordinates. We can pretty much map the entire trajectory without release angles. Like the last unrevealed letter in Wheel of Fortune, you theoretically need it to solve the puzzle, but you can probably infer the word or phrase just fine without it. What are release angles, then, if not just a different way to describe a pitch’s movement in space? What information do release angles add? (Michael Rosen adeptly provided an answer to that question here.)

When a pitcher throws a pitch, the pitch reaches home plate in a fraction of a second. The opposing hitter, then, has a fraction of a fraction of a second to discern a great many things about the pitch: its velocity, its shape, its probable final location, all to then ascertain whether or not he should swing. Given the impossibly small window of time in which to make a swing decision, much of a hitter’s behavior is influenced by the untold thousands of pitches he’s seen before, like a mental library of pitch shapes. One of the very first visual cues a hitter receives, aside from the pitcher’s release point, is the angle at which a pitch leaves the pitcher’s hand. This particular visual cue ought to enable a hitter to determine out-of-hand a prohibitively bad pitch — one that, on most occasions, will not find the zone. He can potentially make a snap decision with a fairly high degree of confidence that the pitch will miss the zone. Read the rest of this entry »

In the course of researching the haphazard nature of JP Sears’ fastball command for my blog Pitch Plots, I realized I was missing the answer to a fundamental question: Why does the ball go where it goes?

Specifically, I had no idea which variables determine the physical location where a pitch crosses home plate. My first guesses revealed nothing: a combination of velocity, extension, spin, and release height had no relationship to a pitch’s eventual location. If it wasn’t any of these factors, what could Sears change to throw his fastball to better locations?

I was missing the key variable: the release trajectory. Trajectory, as defined here, is not just release height and width but also the vertical and horizontal release angles of the pitch, which are not widely available to the public on a pitch-by-pitch basis.

The release trajectory, it turns out, explains nearly everything about the ultimate location of a pitch. Read the rest of this entry »

I won’t sugarcoat it for you, friends. It’s a tough time to be a major league starting pitcher. Their ligaments are under threat like never before. Their workloads aren’t far behind. For a variety of reasons, the old style of starting pitcher is quickly headed toward extinction and we’re transitioning to a new way of doing things.

That all seems like the obvious truth. But I decided to go to the data and make sure. As Malice of the Clipse (and yes, fine, Edgar Allan Poe) memorably said, “Believe half what you see, none of what you heard.” I’m not sure exactly where that leaves you, since I’m going to be telling you what I saw, but that’s an epistemological question for another day. Let me just give you the data.

So far this year, there have been 452 games, and thus 904 starts. Starters have completed 4,735 1/3 innings, or 5.24 innings per start, and they’ve thrown an average of 86.2 pitches to get there. They’ve averaged 94.1 mph with their four-seamers, yet despite all that velocity, they’ve thrown fastballs of any type just 54.9% of the time. This isn’t Opening Day starters, or anything of that nature; it’s just whoever has picked up the ball for the first pitch on each side.
Read the rest of this entry »

On Monday night, I had the privilege of attending a game in which the Reds’ best left-handed starter, Andrew Abbott, faced the Phillies’ best left-handed hitter, Bryce Harper, three times. Abbott got the better of Harper, who went 0-for-3 with a strikeout against the Cincinnati starter and 0-for-5 overall. But the qualities of each player got me thinking.

When Harper swings the bat, one of two things happens. In scenario no. 1, he squares it up and hits it so hard it causes bruising on the deceased ancestors of the workers who stitched the ball together at the Rawlings factory. Sure enough, Harper tagged Abbott’s teammates for three home runs just 24 hours later.

Otherwise, Harper misses it. He can miss it by a lot, in which case he just swings through it, or he misses it by a little. Those swings manifest themselves either in balls fouled straight back to the screen, or in fly balls that go straight up in the air and stay there long enough for the outfielder to take out his phone, and queue up Meat Loaf’s “Bat Out of Hell,” so the ball lands right at the climax of the second chorus. You know the part: “Like a sinner / before / the gates of Heaven / I’ll come crawling on back to you.” The loud one, like five and a half minutes into the song. Read the rest of this entry »

On Monday, I dove into Kevin Gausman’s fast and furious two-strike fastball approach. Last season, Gausman led the majors in terms of the velocity gap between his normal fastballs and his two-strike offerings, and he prospered with that approach. In 2022, however, he had the same juicy gain in velocity and was one of the worst pitchers in baseball with two strikes.

In that article, I mused that it was really difficult to know what pitchers were doing differently with two strikes. Short of using a stuff model, I said, trying to figure out relative pitch quality between two-strike fastballs and their early-count brethren wouldn’t work. Then I had an epiphany. We have a stuff model. We have two, in fact, one of which is entirely in-house. So like a kid asking for the keys to the candy store, I went to David Appelman and asked if I could get pitch-by-pitch stuff grades.

Now I have those! It turns out that running a giant data-focused baseball website comes with access to a tremendous amount of baseball data. I pulled every four-seam fastball thrown in 2023 and broke them into two categories for every player: two-strike counts and all other counts. Read the rest of this entry »

The proliferation of Stuff models has invariably pitted capital-S Stuff against command in terms of their respective importance to a pitcher’s success. If you had to choose one, is it better to locate well, or is it better to be filthy?

The answer to this question is why baseball is beautiful and delightful but also occasionally horribly frustrating. From Vicente Iglesias and Scott Powers:

Importance, in layman’s terms, means how relevant a variable is to explaining an observed outcome; reliability is how much we can expect a variable to repeat or be repeated. In baseball, we often talk about these ideas in terms of “descriptiveness” and “predictiveness.” This dichotomy illustrates the Catch-22 that forever propels baseball forward in all its uncertain glory: pitch location plays an outsized role in determining the outcomes we witness, yet we cannot expect to rely on it year over year. Meanwhile, Stuff is much more reliable next year — i.e., changes to a pitcher’s pitches in terms of velocity, movement, and release point tend to vary to a much smaller degree over time — but it plays a significantly undersized role in influencing actual outcomes this year. Brutal stuff. Why do we even bother? Read the rest of this entry »

Yesterday, I laid out a new method of quantifying depth that we’re looking into here at FanGraphs. It’s based on the idea that while our depth charts are a point estimate of how much each player will play, the real-life way things work is different. To mimic reality more closely, we’re experimenting with removing players from the depth charts algorithmically and rebuilding teams on the fly to see how they look without their best players. Yesterday’s article covers our methodology in great detail.

There’s one thing that I wanted to add to that article but couldn’t find the space for: more tables. There was one big giant table in there that showed each team’s winning percentage as we removed more and more players from their squad. But that’s just not a great way to look at anything – 300 numbers in a giant table is more information than our brains can easily process. I don’t have a lot of new information today, but I thought I’d slice that data up into more bite-sized chunks so you can look at it without your eyes glazing over. One quick note: All the tables in this article are sortable, so you can order them by whichever category you so desire. Read the rest of this entry »

In his recent piece about umpire accuracy, Davy Andrews noted that plate umpires correctly called 99.26% of heart zone pitches in 2023. When I first read that number, I didn’t think missed calls in the heart zone warranted any closer investigation. For most of us, ninety-nine point anything is as good as 100; you don’t spend much time worrying about the 0.01% of germs Purell can’t kill. Then again, if you were to consider the sheer amount of bacteria on your hands at any given moment, you might opt for a second squirt of sanitizer. A tiny percentage of a tremendous number is still going to be a pretty big number. The same is true for missed calls in the heart zone. There aren’t quite as many pitches in an MLB season as there are germs on your phone screen, but there are enough that a few tenths of percent of heart zone offerings still represents a pretty hefty figure. In 2023, plate umpires watched 381 pitches sail over the heart of the plate without signaling a strike. When you frame it that way (pun absolutely intended), it actually sounds pretty bad.

I wasn’t nearly as surprised to learn that plate umpires missed 428 calls in the chase zone last season. Offerings in the chase zone are designed to look hittable out of the pitcher’s hand. An especially talented catcher can make them look hittable as they reach his glove, too. Meanwhile, a batter might like to earn a few extra balls inside the zone, but he doesn’t have the same influence over calls as do his opponents. Besides, if a hitter recognizes that a pitch is coming for the heart zone, he’s not going to wriggle and contort his body in hopes of inducing a missed call – he’s going to swing. To that end, batters are much more likely to swing in the heart zone than the chase zone, which means that on a rate basis, umpires miss significantly more calls over the heart of the plate because there are fewer total pitches there that need to be called. While 381 and 428 are similar figures, batters took 2.4 times as many pitches in the chase zone as in the heart zone. Apparently, it’s harder than I thought to call strikes what they are. Read the rest of this entry »