Going Deep: A Plea to Understand the Struggles of Edwin Díaz

Tim Jackson builds off the Pitcher List Discord community's reaction to Edwin Díaz’s latest meltdown to see if the reliever is possibly tipping his pitches.

Late Tuesday night, September 3, a curious exchange happened in Pitcher List’s delightful Discord channel. The Mets had just imploded, losing to the Nationals, 11-10, in what was either an utterly uplifting or sickeningly defeating walk-off finish depending on your team preference. New York was up 10-4 going into the ninth inning. It was the first time in the team’s 57-year existence in which they lost a game when leading by 6 or more runs going into the ninth inning. Their record in such situations was 806-0.

Community members had the following to say.

Donny M.: “Yo please make the pain stop” – Me, a Mets fan

Alex T.: Wow Mets. 

Alex S.: […] Díaz is absolutely tipping his pitches somehow.

Edwin Díaz had come into the game in the midst of the 9th to stop the bleeding and put the game away for the Mets. Instead, he gave up the three-run homer to Kurt Suzuki that gave the Nats the win. You know by now that Díaz has been dreadful this year, pitching to the tune of a 5.65 ERA and giving up nearly 20% more hard contact than he did last year. Sure, his peripherals are slightly better — a FIP of 4.57 and an xFIP of 3.17– but the results, no matter how we slice them, have been ugly. You might’ve read about how in a certain regard, he’s still elite because his K-BB% is still aces. Maybe you’ve just thought about how relievers are fickle and a BABIP approaching .400 is making this look worse for Díaz. But how much of that matters if he’s unwittingly telling hitters what’s coming? 

Let’s go down that rabbit hole. 




Here’s Díaz in his final appearance in 2018, when he was arguably the best reliever in baseball. There’s a freeze-frame of each his fastball and his slider in the same at-bat. Each one is about as close to the same point in his delivery as possible when playing Statcast clips in slow motion. The red arrows indicate our points of interest here: For the fastball, Díaz’s throwing arm is tucked into his glove between the ring and pinky fingers. This particular pitch finished a strikeout. On his slider, it’s tucked up singularly toward his ring finger. It makes sense, given how different grips require different wrist positioning. This particular pitch went for a called strike before the punchout. 

Below is Díaz this year. 




We have his fastball and slider again, this time in a row to Victor Robles, on August 11. The heater goes for a ball. The slider on the very next pitch gets rocked for a two-run bomb. Díaz’s hands are in pretty darn similar spots as they were last year for each pitch, which pushes this little thought experiment a step further. Maybe this year it’s a little more extreme. Maybe. 

If we can see this sleight of hand from our angle as viewers, how might it be influencing the batter’s look? Are Díaz’s shoulders coming slightly less square on the fastball compared to the slider as he approaches the plate? Can the hitter see the back of his glove raised more on the breaking ball? If Díaz is doing something recognizable before his release point, are hitters allowed to feel more comfortable than usual against high-90s heat and a nasty slide-piece that has two-plane break? 

In his book Full Count with Jack Curry, David Cone says that “the most likely way for a pitcher to tip pitches revolves around how he gets a grip on the baseball in his glove.” Maybe Díaz truly is using the same approach this year that made him a beast in 2018. But it means more eyes have been studying him for longer, meaning more eyes have had a longer chance to find something, even the tiniest little discrepancy in his approach, to use against him. 

A Tale of Two Edwins


We can see that come through in how batters are connecting against Díaz. Remember that note from earlier about how his hard contact, from FanGraphs, has risen dramatically this year? The parameters of hard contact are defined by Sports Info Solutions and aren’t public. But if we consider this contact through the lens of Statcast’s barrel statistic we can more firmly grasp just how hard batters are pummeling Díaz. Barrels are balls hit at least 98 mph, with a launch angle between 26 and 30 degrees, that generate a batting average of at least .500 and a slugging percentage of at least 1.500. 

Díaz has given up more than twice as many barrels this year as compared to last, and nearly three times as many barrels for extra-base hits. Yes, the ball is dramatically different this year. Yes, pitchers can be volatile, and yes, that can be especially true for relievers. Perhaps we could look at each of these season lines for Díaz as an outlier and neither as indicative of his true talent. But even if his true talent is somewhere in the vast middle of his 2018 and 2019 seasons, it’s not hard to imagine his results have catapulted from one end of the spectrum to the other because the opposition has found a way to read his body language. 

Díaz is still generating a top-10 K-BB rate among relievers, which is a huge plus. But when he’s not getting the whiffs or limiting the free pass, the absolute worst is happening. The nature of his position amplifies micro moments more than any other in baseball. “A pitcher’s protective shield [his glove] must be reliable because he only needs to tip one pitch to potentially alter an at-bat and decide a game,” Cone says in his book.

For as brutal as it’s been, Edwin Díaz’s 2019 might be providing another lesson to us about how important even the tiniest details in baseball can be enormously important, and how spotting them can provide critical insight. Or power lots of dingers against one of the game’s best relievers.  

(Photo by Brian Rothmuller/Icon Sportswire)

Tim Jackson

Tim Jackson is a writer and educator who loves pitching duels. Find him in the PL Discord, editing, managing, and podcasting with @BREAKINGPodPL here or writing at Baseball Prospectus.

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