The 2 elite pitches that power the No. 1 free-agent closer

Edwin Díaz, the best reliever on the free-agent market, is a two-pitch pitcher. Fastball, slider, that's it.

And there's nothing out of the ordinary there. Elite closers relying on two pitches is par for the course. But what's interesting for Díaz entering 2026 is how his balance of his two pitches has changed.

Díaz is the best reliever on the free-agent market because he now has two equally deadly weapons.

For a lot of those closers, one of their two pitches does the heavy listing. Take Devin Williams, for example, who just signed with the Mets. Essentially every pitch Williams throws is a fastball or changeup. But his "airbender" changeup has been by far his most dominant pitch over the course of his career.

That was Díaz for a while, too.

When he turned things around with the Mets after his rocky first season in New York, it was because of his slider. Díaz has a 100 mph fastball, but his slider was by far his best pitch by the numbers. From 2020-22, when Díaz had a 2.27 ERA and 15.4 strikeouts per nine innings for the Mets, his slider was generating way, way more value than his four-seamer.

But over the last two seasons, since Díaz returned from the torn patellar tendon that cost him all of 2023, the scales have shifted.

He is still an elite closer -- Díaz has a 2.48 ERA and 13.7 K/9 since 2024. His slider is still a devastating wipeout pitch. But his fastball has stepped up to meet the slider.

Statcast has a "run value" stat for pitchers, which looks at the result of every pitch thrown -- ball, strike, single, home run, strikeout, walk, and so on and so on -- and measures its impact on run prevention. A positive run value means more runs prevented for the pitcher; a negative run value means runs cost to his team.

Díaz's pitching value used to come overwhelmingly from his slider. But now? Díaz's heater and his slider are now equally valuable.

Díaz from 2020-22

• Slider: +36 run value
• Fastball: 0 run value

Díaz from 2024-25

• Slider: +12 run value
• Fastball: +12 run value

That's a big swing. And it's not just that both pitches are equals now -- both are also still top-tier pitches. Díaz ranks right around the top 10 among MLB relievers in both the run value generated by his fastball and by his slider since 2024.

Two powerful pitches are better than one. Díaz's fastball and slider were both always elite from a "stuff" standpoint -- his upper-90s heater has always been explosive, and his upper-90s slider has always been a wipeout pitch -- but he hasn't always gotten elite results from both of them until recently.

So what's been the difference lately? Díaz's slider is still a better swing-and-miss and strikeout pitch, but his fastball has pulled closer. He's also significantly suppressed the damage hitters have been able to do against the fastball and has been holding opponents to a sub-.200 batting average against both pitch types.

Díaz from 2020-22:

• Slider: .132 BA / .155 SLG allowed, 53% whiff rate, 51% strikeout rate, 165 K's
• Fastball: .241 BA / .388 SLG allowed, 34% whiff rate, 34% strikeout rate, 92 K's

Díaz from 2024-25:

• Slider: .182 BA / .304 SLG allowed, 42% whiff rate, 39% strikeout rate, 104 K's
• Fastball: .160 BA / .249 SLG allowed, 38% whiff rate, 38% strikeout rate, 78 K's

The slider numbers for 2024-25 might not be as ludicrous as they were from 2020-22, but they're still really, really good. And so are the fastball numbers.

It's encouraging to see how Díaz has found such a lethal balance between his fastball and slider, because his fastball numbers have improved even as he's lost a little bit of velocity coming back from his injury.

Díaz averaged 98.6 mph on his four-seamer from 2020-22, and has averaged 97.3 mph since 2024. Obviously, that's still high-end velocity. But lower velo carries the risk of more damage allowed, even in the upper 90s, and Díaz has found a way to avert that.

How? Part of it is, he's getting his fastball to more effective locations. From 2020-22, Díaz elevated his fastball -- threw it in the upper third of the strike zone or higher -- just over 50% of the time. Since 2024, he's elevated his fastball 60% of the time. It's easier to rip a heater by a hitter at the top of the zone.

A big part of it is also Díaz's more even pitch mix.

In his most dominant seasons with the Mariners and first few years with the Mets, Díaz leaned on his fastball more heavily before putting hitters away with his slider.

Seeing the completely dominant results he was getting from that slider, Díaz flipped the script in 2022, and just started firing slider after slider. No one could hit it. That was the season Díaz had a 1.31 ERA and 118 strikeouts in 62 innings for the Mets.

But then he got hurt. And when he came back, Díaz adjusted his pitching style.

For the last two seasons, Díaz has been close to a 50-50 split between his four-seamer and slider, against both right-handed and left-handed hitters.

So even with a little less heat on the fastball, and a little less swing-and-miss on the slider, the unpredictability between the two -- particularly when Díaz gets ahead in the count, and in putaway situations -- has let him keep overpowering hitters with both offerings.

The balance, and success, he's achieved with both pitches is not something every reliever can pull off. Díaz is one of six relievers whose four-seamer and slider have both been worth at least +10 runs prevented over the last two seasons.

RP with +10 run value on both 4-seamers and sliders, 2024-25

• Edwin Díaz (+12 on 4-seamers, +12 on sliders)
• Mason Miller (+12 on 4-seamers, +23 on sliders)
• Jason Adam (+11 on 4-seamers, +10 on sliders)
• Carlos Estévez (+14 on 4-seamers, +11 on sliders)
• Alex Vesia (+16 on 4-seamers, +10 on sliders)
• Dennis Santana (+11 on 4-seamers, +11 on sliders)

Díaz isn't your typical two-pitch closer, he's a two-elite-pitch closer. His fastball is electric, his slider is electric, and the combination of the two of them is electric. That's why he's the closer to get in free agency this winter.