Called-Strike-Plus-Whiff Rate (CSW%)
Also known as: CSW%, CSW rate
CSW% is called strikes plus swinging strikes (whiffs) as a share of all pitches thrown. It shows how often a pitcher gets a strike without a ball in play.
CSW% answers a simple question about a pitch or a pitcher's overall arsenal. Out of every pitch thrown, how often does it produce a strike that isn't hit into play? That happens when the hitter takes it for a called strike or swings and misses entirely. By combining both outcomes into one number, CSW% avoids relying on only one of them. Whiff rate alone ignores well-located pitches that hitters correctly take for a strike. Called-strike rate alone ignores pitches with excellent late movement that get chased and missed.
CSW% is popular in modern pitching analysis because it correlates well with overall pitch effectiveness and strikeout rate. It also doesn't need a full plate appearance to resolve. It can be calculated pitch by pitch, so it works for an individual pitch type just as easily as an entire outing. A pitcher or a specific pitch with a high CSW% is generating strikes efficiently, whether through deception, movement, or location. It does so without needing to rely on batted-ball luck.
Example
A pitcher throws 90 pitches in an outing, generating 18 called strikes and 9 swinging strikes — a combined 27 non-contact strikes, or a 30% CSW% for the game.
Why it matters
CSW% gives pitchers and coaches a way to judge whether a pitch or an outing was genuinely effective, independent of batted balls. Results on balls in play are also shaped by defense and luck.
Common mistakes
- Comparing CSW% across very different competition levels without context, since called-strike and whiff tendencies shift with hitter aggressiveness and umpire zone at every level.
- Using CSW% as the only measure of a pitching outing while ignoring walks, hard contact allowed, and overall command.
Frequently asked questions
What is considered a good CSW% for a pitcher?
It varies by level and pitch mix. But a CSW% meaningfully above whatever the typical range is for a given level and competition generally indicates an effective, well-located pitch or outing.
Related terms
- Zone Contact RateZone contact rate is the share of swings at in-zone pitches that make contact. It is a core measure of bat-to-ball skill on pitches a hitter should handle.
- Chase ContactChase contact rate is the percentage of swings at pitches outside the strike zone that make contact. It shows how well a hitter survives a swing at a bad pitch.
- Strikeout RateStrikeout rate (K%) is the percentage of plate appearances that end in a strikeout — elevated K% reduces a hitter's value by eliminating batted-ball outcomes entirely.
- First-Pitch Swing RateFirst-pitch swing rate is how often a hitter swings at the first pitch (0-0) of a plate appearance. It is a simple measure of early-count aggressiveness.
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