Before the season, the San Francisco Giants were expected to be bad, and the Milwaukee Brewers were expected to compete for a playoff spot. So far this year, the Giants are 30-39 with a -82 run differential, last in the NL West. The Brewers are 40-31 and first in the NL Central. Both teams have been more or less what we thought they were. With that in mind, you probably didn’t have much reason to watch Friday night’s Brewers-Giants clash. If you did watch it, however, you caught a singularly bizarre series of plays that highlighted the absurdity and joy of baseball.

In the bottom of the seventh with one runner aboard, the Brewers called on Alex Claudio to keep the Giants off the board. Down 3-2, Milwaukee couldn’t afford to let the Giants pad their lead any further, and the lineup set up perfectly for Claudio, a side-arming lefty with extreme career platoon splits. With Kevin Pillar standing on first, the Giants had four lefties in a row due up, and Claudio is on the Brewers more or less solely to get lefties out.

With Alex Claudio on the mound, there’s a certain minimum amount of weirdness involved in every pitch. His pre-pitch routine is hypnotizing — a few torso-and-arm shakes, an uncontrollable toe tap, and finally a corkscrewing, impossibly angled sidearm release. He looks like a kid impatiently sitting in a doctor’s office waiting room, right up until he explodes into a tremendously athletic delivery. Here, watch him throw an 84-mph sinker past Steven Duggar for the first out:

As much fun as it is to watch Claudio pitch, it would be hard to call this inning fun if he did his job and set down the three lefties in order. The Duggar at-bat made it look like that was a possibility. Even if 84-mph sinkers that strike out major league batters are fun, there’s a limit to how much fun an inning can be to watch if nothing happens. Fortunately, things were about to get weird. Read the rest of this entry »

The Tampa Bay Rays are having a tremendous year so far, better than anyone could have expected. They’re a half game out of first in the perennially difficult AL East, and that might be underselling how good they’ve been this year — their BaseRuns record is the best in baseball. How have they done it? Their pitching staff has been the best in baseball by a huge margin, posting a 3.02 ERA and a 3.34 FIP, both of which are miles better than second place. The hitting has been good, but pitching has the Rays playing like a championship contender.

That pitching staff has been a many-headed monster this year, and Yonny Chirinos has been a key part of it. He’s bounced back and forth between starting and following an opener (headlining?) over 75 innings of work, compiling a 2.88 ERA and 4.05 FIP in his second major league season. He was above average last year as well — a matching 3.51 ERA and FIP over nearly 90 innings. He sports a 21.5% strikeout rate and a sterling 4.9% walk rate. In short, Chirinos looks like a mid-rotation major league starter for the foreseeable future. What’s truly amazing about him, however, is that he’s doing that while being the most predictable pitcher in all of baseball.

If you’re behind in the count against Yonny Chirinos, it’s going to be a long day for you. His splitter, which he only learned in 2017, is lights-out. It’s been the third-most-valuable splitter in baseball this year, behind relievers Hector Neris and Kirby Yates. It generates truly video game numbers: a 45% whiff rate, 2.5 ground balls for every fly ball, and a .155 wOBA on plate appearances that end with a splitter. When Chirinos has the advantage, he’s not shy about going to the split: he throws it 43% of the time, more than twice as often as his overall rate of splitters.

No, if you want to beat Chirinos, you need to avoid the splitter. If you end up in a two-strike count, you’ll probably wave at air before heading back to the bench. Get ahead in the count, however, and things change. Chirinos has an effective fastball, a 94-mph sinker with huge horizontal break that runs in on the hands of righties. Still, it’s a fastball, not a world-destroying offspeed pitch. There’s no question which offering you’d rather face. Read the rest of this entry »

At the start of the 2019 season, the Padres went against conventional baseball wisdom. Chris Paddack, their highest-rated pitching prospect, and Fernando Tatis Jr., their best prospect, both looked ready for the big leagues. Most teams would have left them down in the minor leagues to start the year. They’d have thrown around “working on their defense” or “learning to be a pitcher, not a thrower,” but the reason would be economics. Leave a prospect down for a few weeks, and there’s an extra year of control in it for you on the other side.

The Padres, though, weren’t in the mood for games. Their two highest-paid players lobbied the owner to have Tatis on the opening day roster. Paddack didn’t need a promotional campaign: he struck out 24 batters in 15.1 innings of spring work. His changeup looked dominant. He was ready, and the Padres saw it: he started the fourth game of the season. Skipping service time games and letting your best players play was a revelation, if an obvious one. Paddack started the season with a 1.93 ERA over nine games, Tatis was the team’s best hitter, and “your best players should play” looked like a new and exciting counter to the service-time doldrums.

On Wednesday, the Padres demoted Chris Paddack to the minors. It almost doesn’t matter which level he’s headed to (High-A Lake Elsinore), because he’s unlikely to throw many innings on the farm. The Padres have been cautious with Paddack’s workload this year, only his second season back from Tommy John surgery, and there’s no reason to put stress on his arm against Cal League batters. Indeed, manager Andy Green was quick to mention workload management when describing why Paddack was being optioned:

“Rest is part of the equation. We’ve talked all year long about understanding that Chris had some limitations when it came from pitching from the first day of the season to the last day of the season. We’re cognizant of that. This is a good time to get some work done and get some rest at the same time.”

Sending Paddack to the minors looks odd at first glance. He has a 3.15 ERA and a 3.71 FIP, and he’s probably the best starter on the Padres. Why send him down? Let’s consider a few possible explanations before jumping to any conclusions.
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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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Baseball has changed a lot in the last five years, so much so that watching a game from 2014 already feels like a blast from the past. Offense was low, sinking fastballs were everywhere, and groundballs and defense were the order of the day. 2019 hardly feels like the same game — unless you’re watching Mike Soroka, that is. Though Soroka is only 21 years old, he pitches like he’s from a previous era. In a time of four-seam fastballs, Soroka pitches off of his sinker — he’s throwing only 16% four-seamers this year and 46.3% two-seam fastballs. In a world of exciting high-velocity young aces, Soroka sits around 93 mph. In a world of home runs, he has allowed only one all year. In short, Mike Soroka doesn’t fit in 2019. How does he do it?

As is almost always the case with pitching, Soroka isn’t doing one specific thing that makes him dominant. If it were that straightforward, that easy to reverse engineer, everyone would be doing it. Still, dominant is an apt description of Soroka’s 2019 season. He’s posted a 1.38 ERA over ten starts. His FIP is nearly as jaw-dropping — fifth in baseball at 2.70. Has he been a little lucky that only 2.9% of fly balls hit against him have become home runs this year? Certainly. Still, though, his 3.5 xFIP is no slouch, 20th-best among qualified starters.

Great pitching is always interesting, but the way Soroka is doing it is what makes him unique. His 21.9% strikeout rate is below league average, not the kind of thing you can say about most excellent pitchers. His 6.5% walk rate is better than average, but not absurdly so — it’s merely 38th-lowest among qualified starters. In short, Soroka is an evolutionary Mike Leake, or 2019’s Miles Mikolas. He’s effective in a way that resists categorization, that belies the easy tropes of analysis. Why is Mike Soroka good? He’s good because he gets every little edge he can.
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When Xander Bogaerts played in the 2013 World Series as a 20-year-old rookie, it was easy to see the start of a promising career: he was a glove-first shortstop (though he played mainly third base in 2013, ceding short to Stephen Drew) with enough pop and size to eventually be an impact bat. Over the next four years of his career, though, that promise of power remained tantalizingly out of reach. At the end of 2017, Bogaerts’ career line was nearly exactly average (101 wRC+), but the extra-base hits never quite developed as projected. His .127 ISO was in the 19th percentile of batters with at least 2000 PA over that time period, and his slugging was hardly better (.409, 28th percentile).

Now, a league average bat at shortstop is still tremendously valuable. Bogaerts was worth 12.9 WAR over those four-plus years, a 3 WAR/600 PA pace that would make him a starter on virtually every team. Still, you could look at the promise of a 20-year-old Bogaerts, a 6-foot-1 live wire getting important at-bats on the biggest stage, and wonder why he hadn’t tapped into more offense. It had been four years, after all. Surely if he was going to fill out and add power, it would have already happened.

Two years later, that 2017 endpoint looks awfully conveniently timed to fit a narrative. Since the start of the 2018 season, Bogaerts has found another gear. He’s batting a scintillating .291/.366/.526, good for a 134 wRC+, and the power has miraculously appeared, with his .235 ISO ranking in the 84th percentile among qualifying batters. Still only 26, Bogaerts now looks like one of the best players in the game, full stop. The player fans and scouts saw glimpses of in 2013 is finally here.

What did Bogaerts do to tap into his enormous potential? Well, given that his power numbers have spiked across the board while his strikeout and walk numbers have barely budged (18.5% strikeouts and 7.2% walks 2013-2017 versus 18.1% and 10.2% thereafter), it would be easy to say he just started hitting the ball harder. He always looked like he had the potential to do that. A few pounds of muscle here, a little physical maturation there, a smattering of juiced baseball, and warning track power becomes home run trots. Take a look at Bogaerts’ average exit velocity from 2015 (the first year of Statcast data) to now, on all batted balls and also balls he hit in the air: Read the rest of this entry »

Think back to the first weeks of the season. Those few weeks of time are disproportionately important, because they shape our understanding of the baseball season in a way that two random weeks normally wouldn’t. It’s taken quite a while, for example, for everyone to realize that Christian Yelich is excellent but probably not the second coming of Babe Ruth, or that Paul DeJong is a good shortstop who isn’t one of the best five players in baseball. Marco Gonzales was a no-strikeout pitching phenom, compiling a 3.1 FIP (2.8 ERA) and 1.3 WAR. He’s been below replacement level since, but you wouldn’t know that if you didn’t take the time to look. Yes, the first few weeks of the season exert a powerful hold on our minds.

What if they didn’t, though? What if, for some crazy reason, the first month-plus of baseball didn’t happen, and the season started on May 1? The narratives and the takes would be extremely different. We don’t see them now, because a month of March and April stats camouflage the full-season lines, but here’s a glimpse of what could have been. Read the rest of this entry »

Imagine being a pitcher who has to face the Angels this year. It’s not hard to figure out which batter you most need to prepare for. When the Angels played the Cubs last night, Albert Pujols batted third, which is a lot less imposing in 2019 than it was in 2008. Shohei Ohtani had the night off, which meant that Tommy La Stella was the best non-Trout bat in the lineup. He’s having a good year, as Jay Jaffe noted, but unfortunately for him, he’s still Tommy La Stella. Cesar Puello batted fifth, and hey, good for him. Still, though — the scouting report was probably just Mike Trout written in various fonts over and over again.

It’s safe to say that every game the Angels play, the opposing team has spent a lot of time trying to work out a way to get Trout out. Los Angeles has a robust 109 wRC+ this year among non-pitchers, which sounds good until you realize that non-Trout Angels have a 100 wRC+. The team is scuffling — two games below .500 in a division where you might need 100 wins to topple the Astros, and potentially a little lucky to be there given their BaseRuns record. The pitching staff is essentially made of duct tape and fervent prayers — Ty Buttrey leads the staff in both fWAR and RA/9 WAR, and their starting rotation looks like a horror story told to kids to keep them from becoming Angels fans.

Amidst this chaos, this unending deluge of mediocrity, Mike Trout is putting together another masterpiece of a season. It’s boring to say, almost — his 180 wRC+ is both the fourth-highest in baseball and the lowest Trout has recorded in the last three years. Being one of the best players in baseball is old hat for him. Still, he’s improving his craft incrementally, slowly shoring up weaknesses and adding to strengths. His unintentional walk rate, a gaudy 19%, is the highest of his career. His strikeout rate, a minuscule 16%, has never been lower. Trout’s 2019 might be the best he’s ever hit, a crazy thing to say about undoubtedly the best player in baseball.

Baseball is largely a game of failure and limitations, which makes talking about Trout’s plate discipline feel somewhat surreal. Consider this — Trout has started making contact with basically everything he swings at in the strike zone. His zone contact rate of 94.9% is sixth in baseball and the highest of his career. That’s strange, because for the most part, guys who make contact with everything are contact hitters who sacrifice power to put the ball in play. David Fletcher and his .137 ISO top the list.

This makes a rough kind of sense — hitting everything you swing at in the strike zone means you are probably putting some tough pitches in play, and cutting down on your swing to make more contact means those swings generally have less behind them. That, at least, is the logic that constrains mortals. Mike Trout started hitting everything in the strike zone, and he’s still slugging .600. That slugging percentage might be selling Trout short — he has the highest xSLG (a Baseball Savant statistic that predicts slugging percentage from angle and speed of hits) of his career, a gaudy .643.

What does making contact with every pitch in the strike zone look like? Well, in 2018, Trout was great, but he was great while being only very good against high and outside pitches. Take a look at the upper righthand corner of this chart, the percentage of swings he made contact on by zone in 2018:

Pitchers know about this marginal weakness, and they do their best to exploit it. The book on Trout is to get him high and away. Take a look at where pitchers are attacking him in 2019:

That’s good pitching right there. Find out where a hitter is most likely to get bad results, and aim for that spot. Maybe their focal point is a little too low, but the general idea of throwing away is certainly easy to see. Major league pitchers are tremendously skilled, and they spend countless hours perfecting their craft. That should work out to their advantage, right? Well, bad news, pitchers — this is Mike Trout we’re talking about here. Look at his contact rate in 2019:

It would be one thing to protect a weak point in your swing with some defensive hacks. Plenty of good hitters punch outside pitches the other way, sacrificing power for contact on pitches that are hard to drive. Again, though, Mike Trout isn’t “plenty of good hitters.” He’s the best hitter in baseball. Trout is punishing outside and high pitches in 2019, doing a tremendous amount of damage when he puts the ball in play:

You’re reading this chart right — Trout is now getting his greatest production on balls in play in the very part of the strike zone where pitchers are attacking him most. That, in a nutshell, is what pitching to Trout is like. You might think you’re attacking a weakness, doing your research to put yourself in an advantageous position. Trout’s better at adapting than you are; he’s better than everyone. He reacts to your changes faster than he can be solved.

Pitch location isn’t the only part of Trout’s plate discipline pitchers have focused on this year. They’ve changed how they attack him on the first pitch of a plate appearance, and Trout is yet again using that to his advantage. For years, the book on Trout was that he was patient on the first pitch to the point of somnolence; he basically never swung at first-pitch breaking balls, for instance. Over the past few years, Trout has turned this trend around, becoming increasingly aggressive on the first pitch — he swung at 19.7% of first pitches in 2017 and 18.3% in 2018, the two highest rates of his career.

To combat this trend, pitchers are going out of the zone on first pitches more than they ever have. Trout is seeing strikes on 47% of first pitches, down from his career average of 55% and below the major league average of 51%. This adjustment was largely out of self-preservation. Trout slugged 1.061 with a .485 batting average when he put the first pitch into play last year. He hit five home runs on first pitches, a career high. Sticking with get-me-over first pitch fastballs was no longer an option.

In classic Trout fashion, though, he’s turned pitchers’ adjustments into another tool in his tool belt. Now that pitchers throw him fewer first-pitch strikes, he’s simply swinging less. He’s down to a 17% swing rate on first pitches this year while still swinging at 27% of pitches in the zone. He’s also missing less — he’s swung and missed at five first pitches this year, a 2% rate that would be his lowest since 2015, the last year of his extreme passivity on first pitches. Between this improved swing discipline and pitchers avoiding the zone like the plague, Trout is falling behind in the count 52.9% of the time this year, a career low and 5.2% below last year’s level.

2019 is arguably Mike Trout’s finest batting season so far. His xwOBA of .473 is the highest it’s ever been and 30 points higher than his wOBA, suggesting that he’s been unlucky this year to put up “only” a 180 wRC+, the third-highest of his career. He has the highest walk rate in baseball and a strikeout rate in the lowest 21% of qualified batters. He’s getting on base at the highest rate in his career despite the lowest BABIP in his career (excluding his brief 2011). The two changes pitchers have made to how they approach him this year sure don’t seem to have worked.

Pitchers will try to make other adjustments. They’ll start challenging him in the strike zone more on the first pitch — maybe with offspeed pitches, something that pitchers mostly haven’t tried yet. They’ll aim inside, where Trout’s power is down this year. They’ll continue to hunt holes in his game, small edges that they can use to blunt Trout’s effectiveness.

But until I see some evidence to the contrary, I don’t think it will matter. Pitchers can adjust all they want, try any gambit they’d like. For the most part, it seems like adjusting to beat Trout only plays into his hands. Someday, Mike Trout will grow old. He’ll slow down, get worse at recognizing pitches, stop instilling terror into opposing pitchers the way he does now. That day still feels infinitely far off, though. For now, he’s three steps ahead, putting up unreal numbers while shrugging off regression. Pitchers can plan all they want. Trout won’t stop laughing his way around the bases any time soon.

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 »

Robert Stephenson looked done. After a rocky 2017 (4.68 ERA, 13.8% walk rate), he pitched poorly enough in 2018 spring training that the Reds sent him down to Triple-A Louisville. A vote of no confidence from the Reds, of all teams, is a bad sign for a pitcher. In 2016, the Reds finished 30th in pitching WAR; in 2017, they finished 29th. As Stephenson toiled in Louisville, Reds pitching wasn’t setting the world on fire — the 2018 team finished 26th in WAR, allowing more home runs than every team in baseball other than the Orioles.

When Stephenson returned to the majors at the tail end of 2018, things looked grim. In four appearances, he compiled a 9.26 ERA with more walks than strikeouts. His control, always a limiting factor, looked like it might be his undoing — even in a serviceable Triple-A season, he’d walked 12.2% of the batters he’d faced. As 2018 came to a close, the Robert Stephenson story seemed nearly written. Stuff-first pitching prospect can’t harness his command and never makes good on his promise? Seen that one before. As 2018 was Stephenson’s last option year, he started 2019 in the majors, but time very much felt short.

To understand why Stephenson’s middling major league career was something more than just a journeyman starter’s struggles, you have to look back to his prospect pedigree. In 2015, Kiley McDaniel rated him as the top Reds prospect. In 2016, Stephenson slipped all the way to second. At each turn, though, he showed every tool imaginable. His fastball touched the upper 90s. His curveball was drool-inducing. His changeup wasn’t quite there yet, but you could dream on it. He scuffled in a September call-up in 2016, but for the most part, he looked the part of a future impact arm.

If that was the whole arc of Stephenson’s career, it would be just another cautionary tale about toolsy high school pitching prospects. Sometimes all the stuff in the world isn’t enough, you could tell yourself. Player evaluation is hard! But fortunately for the narrative, that’s not where the story ends. The Reds had to find a place for Stephenson on their 2019 roster, so they turned to the bullpen. Control-challenged starters, after all, are often just relievers waiting to be discovered. What has Stephenson done with the opportunity? Here are the top five relievers this year when it comes to getting swings and misses.

Swinging strike rates this high mostly just look like random numbers, but stop and think for a minute about what this means. A quarter of the pitches Josh Hader throws result in swinging strikes. Not a quarter of the swings — a quarter of the pitches. Stephenson isn’t far behind with his 21.6% rate, and that’s almost as wild. If Stephenson throws five pitches, one is getting a swing and a miss. Hader is a game-breaking curiosity, a mythical bullpen beast who strikes out half the batters he faces and swings playoff series. Robert Stephenson had a 5.47 career ERA coming into this season, and there he is in second place.

Sometimes, relievers are easy to spot. Take a two-pitch pitcher who needs a little velocity boost. Give them an offseason to work on throwing with maximum effort. There you have it, a reliever in a can. So did Stephenson add three ticks to his fastball and start maxing out that wipeout curveball scouts loved so much? Well, yes and no, but mostly no. Stephenson has added a pinch of velocity this year, but he’s not a completely remade pitcher or anything. In 2017 and 2018, his four-seam averaged 93.1 mph in starting appearances. In 2019, he’s dialed it up to 94.2 mph. Maybe he hasn’t gotten a huge velocity boost from relieving, but it’s still something.

When it comes to a secondary pitch, though, Stephenson has made a change. In his 2016 debut, he threw a fastball two thirds of the time, mixing in changeups and curveballs in roughly equal measure. In 2017, he threw a slider for the first time. The pitch was more of a power curve than anything else, thrown with a curveball grip and wrist action closer to a fastball, and it immediately became Stephenson’s best pitch. Batters whiffed at nearly half of the sliders they swung at; not too shabby for a pitch he’d never thrown before.

By 2018, Bob Steve had made the slider his go-to pitch, and analysts noticed. Though he didn’t record many major league innings in 2018, he threw 40% sliders when he did. Of the 99 sliders he threw, 18 drew swinging strikes, a 40% whiff-per-swing rate that beat anything he’d ever done with his curveball. The fastball/slider combination still didn’t produce great results that season, but the bare bones of an impact reliever were there; a decent-velocity fastball, wipeout secondary stuff, a willingness to throw a ton of secondary pitches.

That fastball, however, it’s fair to say wasn’t ready for prime time. By FanGraphs’ linear-weight pitch values, his fastball has been 38 runs below average in his career. It’s hardly better using Pitch Info classifications, at 34 runs below average. These linear-weight pitch values take balls in play, strikes, and balls into account, but the problem with Stephenson’s fastball is pretty straightforward — when batters swing at it, they destroy it. This isn’t a one-year thing, a small sample artifact, or anything benign like that. Every year he’s been in the majors, his results and expected results on contact have been objectively awful.

As you can see, the fastball has been quite poor, even in 2019. Given how much his fastball has been shelled, though, Stephenson’s 2019 is even more impressive. He has a 3.96 ERA and a 2.56 FIP despite a fastball that essentially turns every batter into Cody Bellinger. How has he pulled off that trick? Well, he stopped throwing fastballs, that’s how. Take a look at the qualified relievers who have thrown the most sliders this year.

Want to limit the damage done on fastballs and leverage your excellent slider? Sometimes the solution is pleasingly straightforward — throw as few fastballs as possible, and replace them one-for-one with your best pitch. This play only works in relief, as you can’t exactly throw 60% sliders as a starter, but his slider is so good that even when batters know it’s coming, they can’t hit hit.

Stephenson’s slider is gorgeous when he throws it out of the zone. Jung Ho Kang surely has sliders on the brain here, but still bends the knee.

Keston Hiura manages to get the bat on the ball, but only barely, and the result is the same.

These are the kinds of sliders that end at-bats, and Stephenson is adept at hunting strikeouts with the pitch. He’s getting whiffs on 56% of swings against his slider, a frankly mind-boggling number. But as well as the slider plays as an out pitch, that’s not the only thing Stephenson uses it for.

When Stephenson first developed his slider in 2017, he used it in the way most pitchers use sliders. It came out late in counts as a hammer, a pitch that looked like a fastball early before falling off the table late. While he dabbled with it early in counts, it was largely a pitch to be used while ahead. This year, that dalliance with early-count sliders has become a full-blown romance. Stephenson is throwing sliders to open at-bats 62% of the time in 2019. If the count gets to 1-0, he still goes to his slider 43% of the time. 2-0? Still 42% sliders. On 2-1 counts, Stephenson throws 70% sliders. He’s using the pitch in every situation, whether it’s a traditional slider count or not.

This adjustment is a stroke of genius for someone who can’t afford to let batters tee off on his fastball. As a batter facing Stephenson, you desperately want to avoid a two-strike count, because a two-strike count against Stephenson’s slider is a sure way to end up in a Pitching Ninja GIF. Best, then, to swing at an early fastball. It’s the pitch you want to hit, after all. The next step in that game theoretical confrontation is for Stephenson to throw sliders in fastball counts, and either throw enough for called strikes or be deceptive enough that batters can’t just leave the bat on their shoulders.

Amazingly enough for a pitcher who came into 2019 with a 13.6% career walk rate, Stephenson has pretty good slider command. He’s locating 45% of his first-pitch sliders in the zone, enough that hitters can’t wait him out. His overall slider zone rate of 46% is comfortably better than average (43% for the big leagues as a whole). When he does miss the zone, he’s missing close — he already has nine swinging strikes on out-of-zone sliders to start at-bats this year, the most of any reliever and only three behind slider factory Patrick Corbin for most in the majors.

Though he throws the slider in the strike zone less often than his fastball, the slider has proven to be more effective at managing counts. For his career, he’s located 52% of his fastballs in the zone to open at-bats, a slim lead over the slider. The pitch generates almost no out-of-zone swings, though, which undoes the edge he gets from having more pitches in the zone, and that’s before we even get to what happens when batters do swing. When batters swing at fastballs, they might hit them, and with Stephenson’s fastball, you don’t want that. Take a look at Stephenson’s first pitch outcomes, both in his career prior to 2019 and in 2019.

Those balls in play are mostly fastballs, and letting batters put first-pitch fastballs into play isn’t where you want to be when your fastball is as flat as Stephenson’s. Emphasizing the slider has moved all three results the way you’d like to see them move, and even if it’s a small sample size, it’s encouraging to see such promising first-pitch numbers. The league as a whole has a .364 wOBA after a 1-0 count and a .267 wOBA after 0-1. Those 13% of plate appearances that Stephenson has moved from the 1-0 or in play bucket to the 0-1 bucket are like facing Brandon Drury instead of Ronald Acuña 13% of the time — that’ll do nicely.

Maybe you’re a skeptic. Maybe you think that anything can happen in 25 innings, that the dead can walk and a minor leaguer can look like an effective reliever, if only briefly. Maybe you’d prefer to point to Stephenson’s 3.96 ERA and say that even if this is a new skill level, a high-3 ERA reliever hardly merits a deep dive. I don’t see that, though. I see a celebrated prospect who was legitimately not good enough to stick in the major leagues by doing what he’d done his whole life. I see that celebrated prospect making up a new pitch on the fly, throwing that pitch 60% of the time, and excelling in the major leagues with it. Robert Stephenson was a cautionary tale, and now he’s an impact reliever with a hellacious put-away pitch he can throw in any count. In what has so far been a frustrating Reds season, it’s great to see a former prospect make good.