Sharpe: MLB’s pitch classification system

From Sam Sharpe at MLB Technology Blog on February 3, 2020:

When you’re watching your favorite pitcher in your local ballpark, on your local RSN, or on MLB.TV, it’s unlikely that you’d say he threw a pitch at 88 miles per hour with a 2400 RPM spin rate and two inches of vertical movement above average. You’d say he threw a slider. Using data captured by your eyes, your brain has performed a pitch classification.

MLB performs a similar task in real time for nearly 750,000 pitches each season using patented pitch classification neural network software that is customized for every pitcher in Major League Baseball. The automated classifications for each pitch are displayed on Gameday, At-Bat, and MLB.TV, as well as on local and national broadcasts, on the scoreboards and in-stadium displays in all 30 MLB venues, and on Baseball Savant.

Real-time automated pitch classification began during the 2006 Postseason, when MLB launched the first automated pitch tracking system. The technology was expanded to all 30 ballparks by the start of the 2008 regular season. At first there were only two neural networks used for all pitchers, one for lefties and one for righties. But this model produced disappointing results since each pitcher’s repertoire is different, and even the same pitch will look different when thrown by different pitchers. Some pitchers touch 100 MPH with their fastballs, while others sit in the low 90’s; some pitchers throw slow, looping curveballs while others throw theirs with shorter, harder break.

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Originally published: February 3, 2020. Last Updated: February 3, 2020.