What is CSW Rate? Definition, Formula, and Example
CSW (Called Strikes plus Whiffs) Rate is the percentage of a pitcher's total pitches that result in either a called strike or a swinging strike, capturing both command and stuff in one number.
CSW Rate, in Plain English
CSW stands for "Called Strikes plus Whiffs." It's the percentage of a pitcher's total pitches that either freeze the hitter for a called strike or generate a swing-and-miss. Popularized by analyst Alex Fast at Pitcher List around 2018, CSW% has become one of the most-cited modern pitcher evaluation stats because it captures both *command* (getting called strikes) and *stuff* (missing bats) in a single rate that stabilizes faster than ERA or strikeout rate.
A pitch counts toward CSW if it's either:
- A taken pitch the umpire rules a strike, or
- A swing that misses the ball entirely (a whiff)
Foul balls, balls in play, and called balls do not count. CSW only rewards pitches that actively help a pitcher get to two strikes or finish an at-bat without the batter making contact.
How CSW Is Calculated
The formula is straightforward:
CSW% = (Called Strikes + Whiffs) / Total Pitches × 100
If a pitcher throws 100 pitches in a start with 18 called strikes and 14 whiffs, his CSW for that game is 32%. League-average CSW% sits around 28-29% for starters. Anything north of 30% is good, 32%+ is elite, and the very top of the pitching pyramid lives near 34-35%.
CSW differs from raw swinging-strike rate (SwStr%) because it adds the called-strike component, which credits pitchers whose stuff and location induce taken strikes — front-door breaking balls, perfectly located fastballs at the top of the zone, and back-foot sliders to opposite-handed hitters.
Worked Example: Spencer Strider's Peak Season
In his 2023 Cy Young runner-up campaign, Spencer Strider posted a CSW% near 33% — among the very best marks in the majors. With roughly 3,300 pitches thrown, that translated to about 1,090 pitches that either froze hitters or generated whiffs. His four-seam fastball CSW% was higher still (around 35%), driven by elite extension and ride at the top of the zone.
Compare that to a back-of-rotation starter at 26% CSW: over 3,000 pitches, that's a ~210-pitch gap of "free strikes" — the difference between a 33% strikeout rate and a 19% strikeout rate.
Why CSW Matters
For front offices and analysts, CSW is one of the strongest leading indicators of strikeout rate. It stabilizes after roughly 100 pitches, far quicker than ERA, which needs hundreds of innings. When CSW outpaces a pitcher's actual K%, it signals more strikeouts are coming — and vice versa.
For fantasy managers and DFS players, CSW% separates pitchers whose strikeouts are "real" from pitchers riding hot BABIP or weak schedules. A 30%+ CSW% with a sub-25% K% screams positive regression.
For Legends Deck card ratings, CSW% feeds directly into our Stuff and Command sub-grades — the components that drive simulated swing-and-miss outcomes per pitch.
Limitations and Common Misconceptions
CSW% is not park-adjusted and depends partly on the umpire's strike zone. Pitchers paired with elite framing catchers (Patrick Bailey, Adley Rutschman) get a real CSW boost. It also says nothing about contact quality — a pitcher can have a great CSW but still surrender hard hits when the ball is in play. Always pair it with hard-hit rate and xERA for a complete pitcher profile.
It is also frequently confused with whiff rate, which only counts swinging strikes per swing — a narrower number. CSW is broader and uses *all* pitches as the denominator.
Related Terms
In Legends Deck, every pitcher card carries a CSW-derived "Pitch Quality" rating that influences per-pitch swing outcomes during simulated at-bats — meaning your favorite high-CSW arms generate more whiffs and called strikes in our games, just like they do in real life.