One of the most significant stories of the past few years of baseball has been the changing composition of the baseball. I mean story in the grand narrative sense, but I also mean it in the sense of literal stories. The slice-open-a-baseball-and-catalog-its-contents article has gotten very popular over the last few years, as have studies of drag and bounciness. Physics is having a moment in baseball analysis.

One of the frustrating parts of breaking down the new ball’s effect on offense is that there was no clean way to isolate which hitters were helped most. Many batters adapted their swings to the new ball as the ball kept changing. The ball undoubtedly led to more home runs, as an independent panel reported in 2018. Which batters, though, were the biggest beneficiaries of the new ball? The launch angle revolution might increase batters’ home run rates, but surely a lot of its popularity comes down to the fact that home runs started flying out of the park at elevated rates as the ball changed. Separating cause from effect as swings and baseballs change over years’ worth of games is difficult. Our own Jeff Sullivan took a shot at it in 2016, but didn’t find much evidence for one group over another.

Luckily, this season provides a convenient, natural experiment. To much fanfare, Triple-A switched over to using the major league ball this year. Home runs predictably skyrocketed, driven by the new ball. This creates an opportunity for all kinds of research, such as this attempt by Baseball America to test out whether the ball changes fastball velocity. I thought I’d take the occasion of this new ball to investigate something I’ve always wanted to know about the home run surge: what types of hitters does the new ball help most? Read the rest of this entry »

There are generally three ways of bringing new players into a baseball organization: trades, free agency, and amateur signings, either through the draft or international free agent market. There isn’t necessarily a “best” way, as successful teams are built using a wide variety of methods. The table below shows WAR totals for the first half of the season split into the three categories above, along with waivers and Rule 5 picks, which constitute a very small portion of the total:

As the chart shows, homegrown talent and players acquired through trade come out pretty far ahead of free agency. In terms of the sheer number of players, there are over 400 in each of the homegrown and trade sections, with around 300 in free agency. As for the impact, it’s hard to argue with the importance of homegrown players when looking at the graph above. Breaking the homegrown section down, we can see how each team has done this season with players they’ve drafted or signed internationally and then developed in their organization:

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When the Cardinals played the Marlins on Wednesday night, two of the hardest throwers in baseball made appearances. Jordan Hicks was flawless, getting two strikeouts and four grounders in two perfect innings. Tayron Guerrero pitched a 1-2-3 inning, but with a tad more excitement than Hicks produced. He allowed a fly ball to medium-deep center field, and fly balls are always adventures given the current state of home runs. As I listened to the game, however, the announcers were quick to mention that Guerrero wasn’t in great peril with that fly ball, because it’s hard to hit home runs off of someone who throws so hard.

My statistical curiosity was piqued by that comment. It’s something I’ve heard from time to time, and it seems logical — I’ve watched a fair amount of Hicks appearances in the past two years, and batters seem tremendously uncomfortable when facing him. On the other hand, there are plenty of things I’ve heard about baseball that seem logical but aren’t true. I grew up knowing when the right time to bunt was and how some batters were just better at hitting in the clutch, and those have since been proven false. What’s to say that “throwing harder suppresses home runs” isn’t just another in a list of untruths?

To a certain extent, every time you use xFIP to describe a pitcher’s skill level, you’re ignoring this pearl of broadcaster wisdom. After all, if you’re regressing everyone’s home runs back to a league-wide average, that implies that no one has special skills to suppress home runs when the ball is hit in the air. No one would say that xFIP is a perfect and foolproof predictor, but it does do fairly well when it comes to ERA estimators — it beats FIP and ERA, for example.

As a general believer that skill is over-ascribed in baseball (not every 2.5 ERA or 150 wRC+ is hiding a great process — sometimes it’s just a hot stretch), I’m naturally inclined to go with xFIP’s explanation of how fly balls become home runs. That’s not to say that throwing hard doesn’t have advantages, obviously — baseball’s ever-creeping velocity increase is proof of that. It helps with swinging strike rate, of course, and therefore directly helps increase strikeouts, the most valuable thing a pitcher can do. When the ball is struck, however, the hitter has, necessarily, not swung and missed. In fact, you’ve probably heard people say that when a hard thrower allows contact, it’s usually harder than normal because the ball was coming in so fast. Wouldn’t this increase home runs per fly ball? Sounds like something worth looking at. Read the rest of this entry »

Two things are very much true in modern baseball, and they’re in seemingly direct contradiction with one another. The first hardly requires any introduction: fly balls are leaving parks like never before. There’s almost no point in linking to a story about it, because there’s no way you haven’t heard if you are reading this website, but what the heck, here’s Ken Rosenthal talking about it. Baseball in 2019 is a game of home runs — allow fly balls at your own risk.

At the same time, the two-seam, sinking fastball is going extinct. The trend started a while ago, and it doesn’t look like it’s stopping anytime soon. Cutting sinkers has worked, kind of, and progressive teams like the Astros and Rays are leaning into it. Heck, overhand arm slots and high-spin four-seam fastballs are the hallmarks of modern pitching. Teams are looking for them in draft picks and getting young pitchers to throw more of them.

Think about those two things for a second. Fly balls are more dangerous than ever, but the pitch that is best at avoiding fly balls is on the decline. It’s a mystery worthy of Sherlock Holmes, and today I’m throwing on my deerstalker hat. The first thing we need to do is confirm that fly balls really are worth more than ever. This might seem trivial, but it’s worth doing, if only to figure out just how much more fly balls are worth these days. Read the rest of this entry »

When I wrote about Mike Soroka this week, I mentioned that he’s one of the best players in baseball at getting popups. Nearly 20% of the fly balls opponents have hit against him have ended up in an infielder’s glove, one of the best rates in baseball. It’s clear that this is a valuable skill for the Braves — a fifth of Soroka’s fly balls are automatic outs. But there’s a follow-up question there that’s just begging to be asked. Does Soroka have any control over this? Do pitchers in general have any control over how many popups they produce?

This is the kind of question where it’s important to know exactly what you’re asking. FanGraphs has a handy column in our batted ball stats, IFFB%, that looks like it cleanly answers what you’re looking for. Be careful, though! IFFB% refers to the percentage of fly balls that don’t leave the infield, not the percentage of overall balls in play. Let’s use Soroka as an illustration of this, because his extremely high groundball rate will make the example clear. Take a look at Soroka’s batted ball rates this year:

Soroka allows 19.7% fly balls, of which 17.6% are infield fly balls. In other words, roughly 3.5% of balls put in play against Soroka this year have been popups. For me, that helps contextualize what we’re talking about. Lucas Giolito has the highest rate of popups per batted ball in the major leagues this year among qualified starters, a juicy 7.4% (in a lovely bit of symmetry, teammate and other half of the Adam Eaton trade package Reynaldo Lopez is second). Eduardo Rodriguez is last among qualified starters at 0.5%. There’s a spread in how many popups players allow, but it’s not enormous.
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You’ve surely heard the sentiment: that pitcher is boom-or-bust. When he’s dialed in, he’s unhittable, but sometimes he just doesn’t “have it.” It’s a non-falsifiable claim, of course. It’s nearly impossible to say what constitutes having it or not, and harder still to know if it’s predictive. For the most part, your talent level is your talent level. Great pitcher? You’ll have fewer blowup games. Bad pitcher? Random chance is going to give you your fair share of crooked numbers.

This unprovable fact, however, set me onto an interesting train of thought. What if run clustering isn’t a purely random process? What if some pitchers, not through any innate streakiness but merely by virtue of the outcomes they allow, give up runs in interesting patterns? Take a groundball-heavy pitcher, for example. When a run scores against him, it’s almost certainly due to a series of groundball singles and walks. If one run scores, there’s often another runner in scoring position right away. The state of the world upon giving up one run, for this Zack Britton-wannabe pitcher, is such that he’s immediately threatened with more runs.

Contrast that to a different type of pitcher, a Nick Anderson-style strikeouts and dingers fly ball pitcher. When our punch-outs and fly balls pitcher gives up a run, it’s often on a solo shot. When that’s the case, one run is in, but the resulting situation isn’t threatening anymore. The bases are empty, the damage done in a single instant. Wouldn’t it be reasonable to wonder whether the two allow runs in different bunches?

Still, those are a lot of words with no real evidence behind them. Who’s to say which of those pitchers allow more big innings? Who’s to say if they’re even equally good pitchers? The guy who allows a lot of home runs sounds like he might allow a lot of big innings, just by virtue of being someone who allows a lot of home runs. We need to be more precise to say anything with conviction. Read the rest of this entry »

The height of fashion in baseball analysis three years ago was finding a reliever who could pitch multiple innings. Some people called it the Andrew Miller role, though Miller was never a perfect example of it — aside from the memorable 2016 playoffs, Miller was more of a setup man who occasionally threw the seventh in his tenure on the Indians. Chris Devenski and Chad Green were trendy examples in 2017, and Mets swingmen Seth Lugo and Robert Gsellman both performed admirably in long relief in 2018.

Whichever example you turn to, the value of having a reliever who can perform over multiple innings of work is clear to see. As starters throw fewer innings across baseball, having relievers who can handle larger workloads is increasingly important. A two-inning reliever might have been a luxury in 2009, when a seven-man bullpen would cover two or three innings a night, but 2019 bullpens go eight deep and pick up nearly four innings a game. Using relievers to cover more innings naturally results in weaker relievers getting into games, so getting extra frames out of good relievers has never been more valuable.

That’s the theory, anyway. In practice, the role isn’t easy to fill. If you’re looking for someone to throw a few innings of relief, they have to be a decent pitcher. There’s not really much point in filling bulk innings with replacement-level stuff — you could just use the back of the bullpen for that. There’s just one problem with that: a good pitcher who can throw multiple innings mostly describes a starter, and getting rid of a good starter to create a good reliever doesn’t make that much sense. Blake Snell, for example, would probably make a great reliever, but that would be a waste of his talent. Read the rest of this entry »

Earlier this month, I noted that hitters are chasing fewer pitches and seeking out fastballs in the zone. It’s one thing batters can do to fight back against the rising pitching talent and increased strikeouts. It seemed to me that every time I looked into a hitter potentially breaking out this season, I saw the same pattern: fewer swings on pitches outside the zone and a rising wRC+.

• It was true for George Springer, who took over the AL WAR lead.
• Hunter Dozier seemed to benefit greatly from better discipline.
• Jason Heyward’s mini-resurgence seemed due to better plate recognition.
• Paul DeJong took a step forward by mashing balls in the strike zone and avoiding those outside of it.

There comes a point when writing about the same thing over and over again becomes presumptuous if we can’t quite be sure that the benefits will last. To that end, I first went through plate discipline numbers from this season to determine if chasing fewer pitches seemed to help batters like I think it should. First, I looked at all hitters with at least 300 plate appearances in 2018 who were also qualified for the batting title as of May 13 of this year. While we can presume that taking pitches outside the strike zone is a skill, and one that stabilizes pretty quickly based on previous research, here’s how the numbers from last season and this one match up as of Tuesday’s data. Read the rest of this entry »

Last week, I investigated the changing performance of starters relative to relievers. There’s nothing too crazy about that — FanGraphs is a baseball analysis website, after all, and the starter/reliever divide is a rich topic for analysis. I have to confess, though, that the reception of the article was pretty exciting for me. You see, I got into baseball statistics when a friend recommended The Book to me, and there was Tom Tango, writing about my piece.

Aside from making me feel validated, Tango went over a few methodological improvements I could make to strip a little more noise out of the data. That, in essence, is what all of this analysis is doing — removing noise piece by piece, hoping to find the sweet, sweet signal underneath it all. In my initial article, I covered three topics: pitchers the first time through the order, starters vs. relievers but only using good pitchers, and swingmen. Today, I’d like to look at each of the three with a slightly different aim.

First, let’s talk about performance the first time through the order. Focusing on this consistent set of data (first time through the order, batters 1-7) for both starters and relievers lets us strip out distributional effects from starter workload changes. Merely looking at these splits, however, left out one key factor: home vs. away performance. Mitchel Lichtman has found that home field advantage isn’t a constant — it’s highest in the first inning. Road batters have a pronounced disadvantage relative to home batters in the first inning, which fades away somewhat afterwards. Credit it to having to hit cold, or go the other way and say that road starters are off their game in the first inning, but it’s worth exploring home and away splits to see if there’s anything there. Read the rest of this entry »

If you read about baseball on the internet these days, it’s tough to miss pieces on the changing relative skill levels of relievers and starting pitchers. As Sam Miller pointed out on Effectively Wild, relievers have a higher ERA this year than starters. Not only that, but the strikeout rate advantage relievers have traditionally had over starters is plummeting. Look at almost any statistic, and the historical edge relievers have had over those in the rotation has diminished.

At the same time, relievers are setting volume records left and right. For five straight years, relievers have set a new record for largest share of pitches thrown. In 2012, Rockies relievers struck out more batters than Rockies starters for the first time in baseball history, and you could convince yourself that it was a Coors field oddity. In the next six years, however, four more teams did it. From a bulk perspective, relievers are pitching more and more innings, carrying ever more of baseball’s pitching workload.

Clearly, these two effects are correlated. You’ve undoubtedly heard of the times-through-the-order penalty, the concept that starters fare worse each time through the batting order. In tandem with the innings spike by relievers, the number of pitches starters throw their third time through the order is plummeting. It’s not rocket science — the third time through the order is the time when starters are weakest, and those weak points are disappearing. Of course starters’ stats look better!

Given the changing roles of starters and relievers, it’s probably not right to look at unmodified splits to figure out whether starters are actually getting better relative to relievers. Even if the talent level of every pitcher remained exactly the same, cutting out a chunk of third-time-through plate appearances from starters’ cumulative totals will change their statistics. To actually see whether relievers are getting better relative to starters, we’ll need to do something a little fancier. Read the rest of this entry »