You may have heard that MLB’s Statcast added something new over the weekend: it now has bat-tracking data. There are a bunch of general overviews of what you can learn from this data, so find those if you’re looking for heavy detail, but I’ll just give you the basics. The data tracks things like how fast a player swings the bat, measured in miles per hour, and how long their swing is, measured in feet. (The league-average bat speed is 71.5 mph*, and Statcast considers anything over 75 as a “fast swing.” Average swing length is 7.3 feet.) This data is then used to give us things like “squared-up rate,” which (according to Statcast) “compares how much exit velocity was attained to how much potential exit velocity was possible based on bat speed and pitch speed.”
*Average bat speed considers only the top 90% of a player’s swings in order to keep all the weird check/half/unsure swings from contaminating the data.
Let’s illustrate some of these points by looking at the top five qualified batters in the league right now in squared-up rate:
- Luis Arráez, 43.5%
- Juan Soto, 39.2%
- Mookie Betts, 39%
- Jung Hoo Lee and Steven Kwan, 37.1%
Lee is a bit of an outlier here—he has an OPS of just .641 this season—so we’ll ignore him for now. But Arráez, after a slow start, has his batting average up to .308 and has won batting titles two years in a row; Kwan is leading the American League with a .353 batting average; Soto is hitting .314/.414/.541; and Betts is hitting .339/.441/.539.
