Since coming over in a trade with the Seattle Mariners before 2019, Edwin Diaz has been the most-maligned member of the Mets pitching staff. After a dreadful first season in New York, the flame-throwing righty had a 7.71 ERA through three appearances in 2020 and was demoted from the closer’s role.
Entering Monday, Diaz is quietly working on a stretch of eight straight scoreless appearances, and has only allowed one earned run in his last 12 games. Importantly, that includes three straight scoreless appearances against the Philadelphia Phillies from September 15-17 – the first time he pitched in three straight games since April 2019.
But even as the righty has been re-installed as the Mets closer and he has pitched incredibly well, many fans have a sense of uneasiness when he comes into a game. For sure, some of this is the fatalistic, Murphy’s Law mentality that goes along with being a Mets fan, but Diaz has found a way to not make it easy. His last appearance against Philadelphia is a good illustration:
He loaded the bases on two walks and a hit batsman, but two strikeouts and a groundout bailed Diaz out of the game and sealed the win for New York. No runs allowed, but plenty of agita stirred. It was a nail-biting four-run win for the Mets.
That is the most frustrating thing with Diaz this season. While he has been far less hittable (strikeouts are up, hits and home runs are down), his control has completely failed him at times. In his 2018 All-Star season with the Mariners, Diaz walked 2.1 batters per nine innings. This year, he has walked 5.3 per nine. More on that in a bit, but first let’s look at what has gone right this year.
Statcast loves the season that Diaz has been putting together compared to the league. He is ranked in the top 1% of MLB in strikeout rate (50.0%), xBA (.135), xwOBA (.231), xSLG (.217) and Whiff% (50.5%). Those are the same categories he dominated in from 2016-18 with Seattle, and took a step backward in during 2019. It is a tremendously positive sign.
Fig. 1 – Edwin Diaz Career pitch usage
Diaz’s pitch usage is interesting. For each of his first four years, he was mainly a two-pitch pitcher: a four-seam fastball and slider. But in 2020, he has started to throw a sinker more frequently (more about that in a bit), and it now accounts for 16.7% of his pitches. After throwing three pitches registering as sinkers in 2019, he has thrown 71 so far in 2020.
Statcast shows the average velocity of the sinker has been close to the four-seamer – 97.9 mph to 97.7 mph, respectively – but the difference has been in the break. Diaz’s arm slot gives him good natural arm-side run on his fastball, but the sinker breaks three inches more horizontally and 1.5 inches more vertically than the fastball.
At essentially the same velocity, that extra break is the difference between a whiff and a barrel.
What is interesting about his sinker usage, is that he predominantly uses it against left-handed batters. Of the 71 sinkers thrown, 43 have come against lefties, and 28 against righties. Opposing batters have just a .242 wOBA against the pitch this year.
It is obviously a small sample size, but in 2019 lefties hit .293/.294/.398 against Diaz with a .288 wOBA. In 2020, they are hitting .235/.304/.243 with a .265 wOBA. That is a marked improvement, although in both seasons right-handers have hit him harder.
Importantly, while Statcast registers this pitch as a sinker, PITCHf/x data at Brooks Baseball lumps it in with his fastball. It is quite possible that Statcast is considering a four-seamer with more movement to be a sinker, which is interesting and points more to the differences in the systems than anything else.
One can be inclined to think that the sudden spike in “sinkers” is really just a Statcast error. If it is that is still a good thing. Diaz’s four-seam fastball is showing more horizontal and vertical movement this season than any other season of his career, and so much sometimes that he is “breaking” Statcast.
The extra movement can be a double-edged sword. While it makes his fastball harder to square up, it may be part of the reason for Diaz’s control problems. Only 45.6% of Diaz’s pitches this season have been in the strike zone, the lowest rate of his career. Of the 64.4% of pitches out of the strike zone, opponents are chasing at only 29.0% of them. The average chase rate in MLB in 29.2%, but that number is far below his career rate of 31.5%.
Fig. 2 – Edwin Diaz 2020 Pitch Locations
Hitters are having a hard time making contact against Diaz, but he has had a difficult time getting them to chase out of the zone. Fig. 2 unlocks the key to that. When Diaz misses with his fastball, he misses badly high and away to lefties and high and tight to righties. His sliders out of zone are in a better spot, one of several reasons that his whiff rate is nearly 50 percent higher on the slider.
If Diaz can harness his control, he could unlock being one of the elite relievers in baseball again, a crazy thing to say about someone whose ERA is 1.64 in 2020. With Diaz still under Mets control until 2023, if he can build on the success of this season, he could be the cornerstone closer the team thought it was acquiring in 2018.
Joe Vasile is a play-by-play broadcaster for the Scranton/Wilkes-Barre RailRiders (NYY, AAA) and Bucknell University women’s basketball. He hosts the Views from the Booth and the upcoming Secondary Lead podcasts.