This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: In baseball, a borderline pitch is more likely to be called a strike when the batter has three balls and no strikes than when the count is no balls and two strikes. The official strike zone hasn't changed.
The umpire's judgment has. The outcome can have a major impact. A fourth ball sends the batter to first base, while a third strike ends the batter's turn.
But an analysis of more than 450,000 Major League Baseball pitches suggests that the shifting calls may partly reflect something more basic: how the brain combines uncertain visual information with expectations. For their study published in Communications Psychology, the model created by Mitsuto Tomomura and Masahiro Shinya of Hiroshima University reproduced the call patterns during pitch counts, and found a crucial clue coming from the pitches that batters chose to let pass. When a batter doesn't swing, the umpire judges whether the pitch passes through the strike zone over home plate.
To map how that judgment changed with the count, the researchers analyzed tracking data and calls from the 2015–2024 seasons. They restricted their study to four-seam fastballs thrown by right-handed pitchers to right-handed batters, keeping pitch type and handedness consistent. At each of the zone's four edges, they estimated the boundary where a pitch was equally likely to be called a ball or a strike.
They found that the next borderline pitch after three balls and no strikes was more likely to be called a strike (an expansion of the effective zone in the eye of the umpire). When the count was no balls and two strikes, the pitch was more likely to be called a ball (a contracted zone). But the umpire wasn't the only person responding to the count.
With two strikes, a batter has good reason to swing at a borderline pitch: Letting it pass risks a strikeout. That leaves the umpire judging a different selection of pitches, tending farther outside the zone. This distinction mattered to the model.
Extract — continue reading at the source.
