When is unnecessary delay charged to the offending team?

Unnecessary delay is charged to the offending team when there is a substitution delay. This situation typically arises when a team takes too long to substitute players into the game, which can disrupt the flow of play. Volleyball rules emphasize the importance of maintaining the pace of the game, and an extended delay in substitutions can lead to a break in action, affecting both teams’ rhythm. When such a delay occurs and it is determined that it is unnecessary, the referee has the authority to charge the team with this infraction, passing the responsibility for the delay back to the offending team.

In contrast, while injuries may require time for assessment and care, they do not typically lead to a charge of unnecessary delay as they are often unavoidable. Similarly, a coach’s dispute with a referee, while possibly creating a delay, also falls within a different context of game management and is not automatically considered unnecessary. Finally, the readiness of game balls is generally a procedural matter handled by the officiating crew and does not directly link back to a team's actions in a way that would warrant a delay charge. Thus, the act of delaying substitutions directly ties into team management and game flow, supporting why this is the correct answer.