Know Your Averages 2024, Slider Edition

Toward the end of the 2024 season, I aggregated fastball performance metrics with “Know Your Averages 2024” and wrote about the pitchers near the minimum, the maximum, and the average. For example, Aroldis Chapman’s sinker still rules the SwStr% category (maximum, 17.8%), while Jake Woodford couldn’t buy a swinging strike (minimum, 0.9%) and George Kirby was perfectly average (6.0%). Below, you can find links to those posts. You may find them useful when contextualizing the statistical vomit coming from any baseball podcaster’s repertoire. I needed to do it for myself:

Fastballs: Four-seamers | Sinkers | Cutters

But now we move beyond the fastballs and attempt to digest all those other pitches. There are tremendous differences in the fastball swinging strike rates around and below 10% and the 15%’ers of sliders and splitters. We’ll begin with sliders.

Breaking and Offspeed Pitches: Sliders | Changeups | Curveballs | Splitters | Sweepers

My process relies on Alex Chamberlain’s Pitch Leaderboard which utilizes Statcast data that you can also find at Baseball Savant and our (New!) Pitch Type Splits on player pages. Here is a quick look at how the slider stacks up against other non-fastball pitches in several measurements:

Ben Clemens wrote about sliders in two parts back in 2021. If my analysis of slider performance makes you confused and in need of aspirin, go read those articles and you’ll feel better. This is because a good slider can be difficult to define. As you’ll see, pitchers utilize their sliders in different ways and find varied paths to success. Go figure! Let’s look at the pitchers below, at, and above average with their sliders in each measurement. A lot of what follows in the “Questions or comments?” section is less analysis and more points for further research or discussion.

NOTE: The chart and table above do not include a minimum pitch qualifier. The players in the analysis below will fall under a 40-pitch minimum qualifier with some arbitrary author finagling.

—Zone%—

• Yu Darvish – 62.1%
• Max Fried – 45.7%
• Chris Flexen 플렉센 – 26.1%

Questions or comments?: You must bring down the qualifier threshold on the Statcast Pitch Arsenal leaderboard for Darvish’s slider to appear. It appears all right, in the center of the zone. Often. It returned a Run-Value of only two and was slugged at a .478 clip, resulting in five home runs. It’s tough to say if Darvish’s 81.2 IP allowed him to get the feel for his slider or not, but its movement profile has changed over the years, and the zone may not be the best place for a pitch with a movement profile very close to average. In the Ben Clemens article I referenced earlier, one of his biggest takeaways was that “[b]ig, sweeping sliders excel over the heart of the plate” and Darvish’s is no longer big or sweeping. In its heyday Darvish’s slider had nearly four inches of vertical drop compared to similar pitches according to Statcast. In 2024, it dropped less than one inch more than similar pitches.

Max Fried’s current slider gets over five inches of vertical drop versus the average and was utilized only 5.6% of the time in 2024. What about Flexen? It may not have been in the zone much in 2024, but hitters chased after it at accelerated rates. The pitch’s 31.3% O-Swing was above average and Flexen’s version enticed hitters to chase as it had more drop and break than average. That may not be the way to go moving forward, for Flexen’s slider performed much better when it was thrown in the zone:

Granted, Flexen only threw 35 sliders in 2021, but there exists a big enough sample in 2022 to suggest Flexen should consider moving his slider back into the zone.

—Swing%—

• Mitchell Parker – 60.6%
• Graham Ashcraft – 48.4%
• Alex Wood – 27.7%

Questions or comments?: The 25-year-old Mitchell Parker threw his slider 236 times in the 151 innings he pitched for the Nationals in 2024. That was a lot of innings! By Stuff+, his slider was his best pitch by SwStr%, Contact%, and O-Swing%. But he used it only 10% of the time. 49% of the time he threw a “not-so-good” fastball. He had one of the highest swing rates on his slider but finished with one of the 50th-best xwOBAs (.238) on the pitch among pitchers who threw a slider in at least 50 plate appearances. Graham Ashcraft’s average Swing% slider did slightly worse in the xwOBA department at .249 and Alex Wood’s demonic, 9.8-inch dropping (vs. AVG) slider garnered the “worst of all” .252 xwOBA. These three pitchers demonstrated similar xwOBAs on their sliders while utilizing them in very different ways.

—SwStr%—

• Max Scherzer – 26.4%
• Tarik Skubal – 15.2%
• Trevor Williams – 2.1%

Questions or comments?: Though he only threw 43.1 innings in 2024, the 148 sliders Max Scherzer threw were good enough to finish in the top 50 (42nd) in Whiff%. Remember that Statcast calculates Whiff% as “Swings and Misses / Total Swings” and SwStr% as “Swings and Misses / Total Pitches”. Both measure strikes and Scherzer’s slider got them. But, like Darvish, Scherzer’s slider has lost some of its movement with time and grades out from Stuff+ as a below-average offering. In 2023, Scherzer gave up 10 home runs off sliders, but in 2024 it gave up only one. It’s possible that an excellent July 25th outing against the White Sox gave Scherzer’s slider a boost that appears exaggerated in a small sample.

Skubal used his slider, his worst pitch according to Stuff+, the least amount of time (15%). Still, it produced average results. I’ll write that out more clearly; even his worst pitch was on par with the major league average! What does that tell you? Finally, Trevor Williams threw his best pitch (115 Stuff+), the slider, 35% of the time. Well, he threw his four-seamer a little more often at 36% of the time, but somehow he produced one of the lowest slider-swinging strike rates in 2024. This is mostly a complication of Williams’ slider and sweeper results being clumped together on his player page. Williams’ sweeper results carried his slider results in this case:

Slider: 5.9% Whiff%, .353 wOBA, .356 xwOBA, 52.0% HardHit%

Sweeper: 45.9% Whiff%, .179 wOBA, .210 xwOBA, 13.6% HardHit%

The sweeper was the better pitch and Williams may have found something in it late in his career, but with a poor-performing fastball and likely some good luck behind his batted ball results in 2024, don’t expect a repeat in 2025.

—CallStr%—

• Trevor Williams – 26.4%
• Grayson Rodriguez – 14.7%
• Cole Irvin – 1.6%

Questions or comments?: Hey! There’s Trevor Williams again! It’s most likely that his added sweeper usage had something to do with his elevated called strike rate. Perhaps hitters were sitting on his fastball and giving up the zone to the slider/sweeper combo. Cole Irvin’s 62 sliders were thrown in the zone often (~+5% vs. AVG), and swung on often (~+14% vs. AVG) with a zone contact rate of 97.1%. He didn’t get called strikes because hitters swung and connected almost every time. He’s pitching in Korea in 2025.

—CSW%—

• Spencer Strider – 45.6%
• Dane Dunning – 29.8%
• Chris Bassitt – 17.2%

Questions or comments?: Strider only threw 57 sliders, but wow they were good. When it was in the zone, hitters only made contact 55.6% of the time. That’s incredible, and it was in the zone often at 50.9%. Oddly enough his 2024 slider (more rise, less break) appeared to be much different from his 2023 slider (more drop, more break). 2024’s version was more of a “come and get some” type of approach and it will be interesting to see how the pitch comes out in 2025.

What’s not listed in the table above is Contact%. According to Alex Chamberlain’s leaderboard, the average was 34.2% and Dane Dunning’s sliders came into contact with bats 71.6% of the time. What percentage of the time did that result in good contact? PitcherList’s Ideal Contact Rate (ICR%) “is a metric that essentially tells us how often a batter made ‘good’ contact on the ball” and hitters got to Dunning’s slider for a 45.5% ICR compared to the average 38.6%. Chris Bassit’s 2024 slider had a decent amount of vertical drop, but he may have put it in the zone too often. It produced a -6 Statcast Run-Value in 2024.

—Chase%—

• Yonny Chirinos – 12.9%
• Ronel Blanco – 24.9%
• Nick Pivetta – 35.2%

Questions or comments?: Here’s a look at each slider and its Statcast movement profile courtesy of Baseball Savant:

Chirinos’ slider encouraged less chase, yet had more break than average. Blanco’s slider was chased at an average rate, and it had less break and less drop than the average. Out of these three, thank god for Pivetta because at least his slider makes sense. The massive drop in his slider movement encouraged hitters to chase. In the case of Yonny Chirinos, things are a little more explainable as he threw his slider in the zone 62.2% of the time. That’s over 15% more than average. It’s impossible to have hitters chase your pitches when you throw them in the zone.

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Sliders are challenging to evaluate. Some are sharp and hard like Spencer Strider’s version. Some are loopy, lofty, and cartoon-like as Nick Pivetta’s. Just looking at the Statcast pitch movement leaderboard’s most drop-heavy sliders will show you a real mix of pitchers. The story goes further than simply asking, “How much does your slider move?” As much as we may attempt to create one, there really is no recipe for being a great pitcher. A good slider will help, but good luck defining “good”.