Balks is an infraction called in baseball when a pitcher makes an illegal motion or action prior to a pitch with the intention of deceive the hitter or runners. If there are runners on base, the runners will be awarded an additional base.
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A “balk” in baseball is defined as when a pitcher makes an illegal motion on the mound while there are runners on base. When a balk is called the play is dead and all baserunners move up one base. The balk rule is one in which many fans claim to know but is often difficult to detect, and many discussions between umpires and managers have taken place about whether a movement was illegal. Balks are overall relatively rare and relievers have more balks on a per inning basis than starters. The balk rule has not changed often over time, though starting with the 2013 season a balk was called when a pitcher would step towards third base and fake a throw to first base with runners on the two bases.