Avoidance of Fielder: A runner leaving their feet to avoid a fielder who:

Is in possession of the ball.

Is in the act of fielding the ball.

Is considered an illegal act.

Consequences:

The ball is declared dead.

The runner is called out.

No runners may advance from their last legally occupied base.

Important Notes: Contact between the runner and fielder is not required for the act to be considered illegal. The fielder does not need to have full control of the ball for the act to be considered illegal.