Whiff rate
also: swinging strike rate per swing · whiff %
Swinging strikes as a share of swings: how often a pitch makes hitters miss when they go after it.
Formula
whiff rate = swinging strikes / (swinging strikes + fouls + balls in play)Computed per pitch type in a pitcher's arsenal, it shows which pitch is the out pitch. A slider with a 40% whiff rate and a four-seamer at 20% is a familiar shape.
We count a swing as a swinging strike, a foul or a ball put in play, from ESPN's pitch-by-pitch result on each pitch.
The common mistake
Whiff rate ignores pitches that are taken. A pitch hitters never swing at can post a high whiff rate on a handful of swings and still be a ball most of the time; read it with ball rate.
Where to get it
Related
Whiff rate from the API
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