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Expected Hits Model

Summary​

Model the probability of each outcome of a batted ball (out/1B/2B/3B/HR) based on exit data and use those probabilities to calculate expected batting stats like xAVG, xSLG, and xwOBA. 

We use separate models for seasons 2020+ (Hawk-Eye) and prior seasons (Trackman) to account for differences in the tracking systems.

Inputs​

This model is based on batted balls from the 2019-2023 MLB regular season. The inputs differ by launch angle, exit velocity, and exit direction and include

  • Batter hand

  • Exit velocity

  • Estimated distance of batted ball

  • Estimated hang time of batted ball

  • Estimated speed of the runner to first base (Statcast games only)

Key Metrics​

x1B%/x2B%/x3B%/xHR% - Expected rate of 1B/2B/3B/HR based on model output. Available from batter, pitcher, and catcher perspectives.

xAVG - Expected AVG based on expected rate of 1B/2B/3B/HR outcomes. Available from batter, pitcher, and catcher perspectives.

xOBP - Expected OBP based on expected rate of hit outcomes. Available from batter, pitcher, and catcher perspectives.

xSLG - Expected SLG based on expected rate of 1B/2B/3B/HR outcomes. Available from batter, pitcher, and catcher perspectives.

xOPS - Expected OPS based on xOBP and xSLG. Available from batter, pitcher, and catcher perspectives.

xISO - Expected ISO based on expected rate of 1B/2B/3B/HR outcomes. Available from batter, pitcher, and catcher perspectives.

xWOBA - Expected wOBA based on expected rate of 1B/2B/3B/HR outcomes. Available from batter, pitcher, and catcher perspectives.