Called-Strike-Plus-Whiff Rate (CSW%)
Also known as: CSW%, CSW rate
CSW% is a pitching metric that combines called strikes and swinging strikes (whiffs) as a share of total pitches thrown, measuring how often a pitcher generates a strike without the ball being put 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 — either because the hitter takes it for a called strike or swings and misses entirely? By combining both outcomes into one number, CSW% avoids relying only on whiff rate (which ignores well-located pitches hitters correctly take for a strike) or only on called-strike rate (which 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 without needing a full plate appearance to resolve — it can be calculated pitch by pitch, which makes it useful for evaluating 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, 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 batted-ball-independent way to judge whether a pitch or an outing was genuinely effective, rather than relying on results that were also shaped by defense and luck on balls in play.
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 percentage of swings at pitches inside the strike zone that result in contact — a core measure of basic bat-to-ball ability on pitches a hitter should be equipped to handle.
- Chase ContactChase contact rate is the percentage of swings at pitches outside the strike zone that result in contact, measuring how well a hitter defends the plate even when they have made the decision to 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 the percentage of plate appearances in which a hitter swings at the very first pitch (the 0-0 count), used as a simple measure of a hitter's early-count aggressiveness.
Related guides & benchmarks
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