What should an umpire do if they observe a player obstructing the runner returning to a base?

When an umpire observes a player obstructing a runner returning to a base, the appropriate action is to award the runner additional bases. Obstruction occurs when a fielder who does not have possession of the ball interferes with a runner's opportunity to advance. In this situation, the runner has a right to the base they are attempting to return to, and any illegal obstruction warrants a penalty. The rule is designed to protect the runner's right to advance and ensure fair play on the field.

Awarding additional bases helps to mitigate the impact of the obstruction and allows the runner to recover from the interference. This action aligns with the rules of baseball, which prioritize ensuring that the player is not unfairly disadvantaged by the obstruction, thus maintaining the integrity of the game.