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Baseball Balk Rule: What Pitchers Are Not Allowed to Do

With at least one runner on base, a balk is an illegal pitching action governed mainly by Official Baseball Rule 6.02(a). Common triggers include starting and stopping a delivery, failing to come to a complete set, deceptive feints or throws, failing to step toward a base, and certain disengagement violations.

Timeline

  1. Before the motion: Identify whether runners are on base and whether the pitcher is using the windup or set position while touching the rubber.
  2. Pitch or pickoff action: The umpire judges the stop, step, throw, feint, disengagement and whether the movement commits one of Rule 6.02(a)’s listed acts.
  3. Enforcement: Play may stop or continue under the balk exception; runners normally receive one base, with later advances made at their own risk.

A balk is an illegal act by a pitcher when at least one runner is on base. Its purpose is to prevent the pitcher from deceiving runners with a motion that improperly imitates a pitch or pickoff. The list appears in Official Baseball Rule 6.02(a), so “the pitcher fooled the runner” is not enough by itself; the umpire identifies a prohibited act. With no runners, similar conduct may instead be an illegal pitch or another violation, not a balk. [1][2][3]

From the set position, the pitcher must come to a complete stop before delivering. Once the pitcher makes a motion naturally associated with the pitch while touching the rubber, failing to deliver is a balk. Interrupting or altering the delivery after commitment, making a quick pitch, or habitually using a motion without the ball while on or astride the rubber can also violate the rule. Umpires judge the whole continuous action, not a still photograph. [1][3][4]

Pickoff actions have their own limits. While touching the rubber, a pitcher must step directly toward a base before throwing there. The rules prohibit feinting a throw to first or third and failing to complete it, while a legal move to second can differ because of the play and base involved. Throwing or feinting to an unoccupied base is generally a balk unless the pitcher is making a play. Details vary with which foot disengages the rubber. [1][3]

MLB’s pitch-timer rules add a counted disengagement. A step-off or pickoff attempt is normally a disengagement, and pitchers are limited to two per plate appearance; the count resets if a runner advances. A third disengagement is a violation and results in a balk unless an attempted pickoff retires the runner. Mound visits and certain timeouts are treated separately. Other leagues and amateur codes may use different limits, so this guide describes MLB’s professional rules. [1][2][5]

A balk does not always erase everything that follows. Rule 6.02(a)’s penalty normally makes the ball dead and awards each runner one base. But if a pitch or throw follows and every runner, including the batter-runner, advances at least one base because of the play, the play proceeds without reference to the balk. A runner who safely reaches the awarded base may continue beyond it at personal risk, which can make enforcement look different from a simple automatic advance. [1][3]

Other listed balks include delivering while not facing the batter, making a pitching motion while not touching the rubber, unnecessarily delaying the game, dropping the ball while touching the rubber when it does not cross a foul line, and certain catcher positioning violations during an intentional base on balls. The rule is a catalog rather than one visual test. Announcers may summarize the call by saying “no stop,” “started and stopped” or “failed to step.” [1][3]

To analyze a clip, first confirm a runner was aboard, then note the pitcher’s position, pivot foot, first committed movement, direction of the step and destination of any throw or feint. Check whether the plate appearance had already used its disengagements and what happened after the call. The umpire’s judgment controls the game, and competition rules can supplement MLB’s code. Use the current Official Baseball Rules rather than a youth-league summary for an MLB play. [1][2][5]

Sources

  1. Major League Baseball — 2025 Official Baseball Rules
  2. MLB Glossary — Balk and Disengagement Violation
  3. MLB — What Is a Balk? A Guide
  4. MLB Glossary — Set Position
  5. MLB — 2026 World Baseball Classic Rules and Modifications

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