GUIDES · BETSLIP DOCTOR
Why should fast-swing rate and swing length be read as different measurements?
Fast-swing Rate is the percentage of all swings that reach at least 75 mph. Swing Length is the distance, in feet, traveled by the bat barrel from the start of tracking through impact. One is a thresholded share of swings; the other is a path length.
For Bettors and cappers learning to read baseball records · Updated
Swing Length measures the barrel’s route
Swing Length sums the distance the bat barrel travels through X, Y and Z space from the start of bat-tracking data, generally around 150 milliseconds, until impact. The result is a distance in feet. A swing can travel a longer path without crossing the 75 mph speed cutoff, and a shorter path can still meet it.
For comparison, keep the same swing set and report both the all-swings denominator for Fast-swing Rate and the path-length measurement. Do not treat either as a recommendation for a particular swing shape.
Two fictional ten-swing samples
Hypothetical samples: Batter A has 10 tracked swings; 7 reach at least 75 mph, so the Fast-swing Rate is 7 divided by 10, or 70 percent. The mean Swing Length across those same 10 swings is 7.2 feet. Batter B also has 10 swings; 4 reach at least 75 mph, so the rate is 40 percent, while the mean path length is 8.1 feet. These invented summaries show that a longer average bat path and a higher fast-swing share are separate observations, not interchangeable measures.
Related questions
Does a longer Swing Length mean a swing was fast?
No. Swing Length is bat-barrel travel in feet; Fast-swing Rate counts the share of swings reaching at least 75 mph.