Fastballs are being thrown less than half the time for the first time in recorded MLB history, replaced mostly by sliders.
Why it matters: The increasing prevalence of sliders has contributed to the league-wide batting average decrease. This year's mark, .242, is the lowest since 1967.
By the numbers: While fastball usage has declined from 57.7% to 48.8% during the Statcast era (2015-present), slider usage has increased from 14.7% to 22.2%.
- Batters aren't thrilled with that role reversal: Entering Monday, they were hitting just .209 against sliders this season.
- That's the lowest mark of any of the five pitches thrown at least 2% of the time (fastball, slider, curve, changeup, cutter).
Between the lines: Sliders are essentially faster curveballs with less movement (or slower cutters with more movement). When the pitch first came to prominence in the 1910s, it was referred to as a "nickel curve."
- While curveballs break vertically and are thrown with a downward yank, sliders "slide" laterally and are thrown with a special grip and finger pressure.
- The risk: If a slider doesn't break as much as a pitcher hopes, it "hangs" in the strike zone, allowing hitters to tee off on a pitch with fairly straight trajectory and sub-fastball velocity.
What they're saying: "It's not just the volume of sliders that's on the rise — it's the quality," writes SI's Tom Verducci. "Thanks to high-tech pitching labs and coaches skilled in biomechanics ... the average slider spins 14% faster today than it did in 2015."
- "Moreover, in that same time pitchers have added five inches to their extension on sliders — the point where they release the pitch."
- "More extension means less time for a hitter to react and more finish on the break of the pitch."
The bottom line: Sliders are having a moment. That's bad news for hitters.