K-bb and Strike Zone from Same Data

MLB Umpires each call distinct strike zones depending on the game condition and what side the batter is standing on. Here we show the area of the called strike-zone for each umpire in the MLB with over 50 games called since 2017 seperately for Left and Right handed batters. These strike zones are only calculated on ODD seasons {so 2017, 2019, 20221, 2023}. This is plotted against the stike-out (k) to walk (bb) ratio for each umpire calculated over the same time period. The two show a clear positive correlation.

You can hover over each point to see the umpire's name. Blue points correspond to left handed batters and red points correspond to right handed batters.

Held Out Data

Here we visualize the same relationship but with k:bb ratio calculated using data from only even seasons {so 2018, 2020, 2022, 2024}. This removes the aspect of the previous graph that is circular (as they are based on the same data). The continued positive correlation of a similar magnitude shows that umpire strike zone size is consistent accross seasons and may be predictive of game outcome.