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While the official MLB rule book does not have an official definition of what constitutes a swing, most baseball fans, umpires, and former players typically agree on the same definition.
A batter is often deemed to have swung is his breaks breaks parallel with the front of home plate. That is almost always the way that first and third-base umpires have called check swings.
However, it turns out that we may have been wrong the entire time. The newly implemented check swing challenge system in Minor League Baseball is officially defining what a swing is, and it’s nowhere near what we thought.
Check swing challenges are now a thing at Triple-A
Dodgers infielder Hyeseong Kim successfully used one on Sunday pic.twitter.com/w2poobVg8m
— Jomboy Media (@JomboyMedia) June 1, 2026
New Check Swing Challenge System Gives Huge Advantage To Batters
Major League Baseball first tested a check swing challenge system in the Arizona Fall League before adding it to the Single-A Florida State League in 2025.
This season, the challenge system has expanded to the Triple-A Pacific Coast League.
Over the weekend, Los Angeles Dodgers’ minor leaguer Hyeseong Kim used the challenge system in a game for the Oklahoma City Comets. Kim was initially called out after the umpire ruled that he swung for the third strike of the at-bat.
However, upon review, the challenge system deemed that Kim did not make a swing attempt.
#Dodgers Hyeseong Kim takes advantage of the new check swing challenge. He gets on base for Tommy Edman to drive him home. pic.twitter.com/q7xL22G8ql
— Dodgers_After_Duty (@msalas24) May 31, 2026
There’s just one major issue with the ruling, and the system as a whole.
According to the Automated Check Swing system, a batter only makes a swing attempt if their bat goes further than 45 degrees past the front of home plate. Or, in other words, if their bat crosses the plane of the third/first base line.
That gives hitters a ton of latitude to pull their bat back before officially making a swing, and fans are flummoxed.
“If that’s the line that constitutes a swing, there will never be a non successful challenge,” one fan said on X.
“Apparently, my whole life I never knew what a swing actually was?” asked another.
So, what do you think? Is the challenge system wrong? Let us know in the comment section below.