When is a baseball considered legal even after being fouled off and having a dark smudge mark?

A baseball can be considered legal even after being fouled off and showing a dark smudge mark if the umpire detects no issues with the ball. This means that the ball has not been damaged in a way that affects its performance, such as being excessively scuffed, deformed, or otherwise altered. Umpires are trained to assess the condition of the ball during the game and make judgment calls about its legality based on specific criteria.

The presence of a smudge alone does not inherently render the ball illegal, as long as it does not obstruct the ball's playability. The focus is on the integrity and overall condition of the ball, ensuring that it still meets the standards required for play. Thus, if the umpire is satisfied that the ball remains fit for use, it can continue to be used in the game despite the smudge from a foul ball.