How it works
The rules regulate how a pitcher comes set, disengages from the rubber, stops, steps toward a base, and delivers the pitch. Several distinct violations can be called a balk.
What people often miss
There is no single motion that defines every balk. Context matters, and similar-looking actions may be legal when the bases are empty.
Why this question comes up
Even experienced fans find balk calls confusing because they involve technical details that happen quickly.
Key points
- A balk is an illegal pitching action with runners on base that can deceive or disadvantage them, usually resulting in runners advancing one base.
- The rules regulate how a pitcher comes set, disengages from the rubber, stops, steps toward a base, and delivers the pitch. Several distinct violations can be called a balk.
- There is no single motion that defines every balk. Context matters, and similar-looking actions may be legal when the bases are empty.
Bottom line
A balk is an illegal pitching action with runners on base that can deceive or disadvantage them, usually resulting in runners advancing one base.
Source and verification
This Answer was checked against Major League Baseball. Follow the source for the full official explanation and any later updates.