Numerous athletes across several disciplines use a crossfit plyo box regularly for their training. It provides them with the strength and conditioning that they need for the crucial moments of the game.
For example, volleyball players are always engaged in aerial combat. The spiker faces the blockers for the precious points. The aggressor wants to jump as high as possible to clear the wall. The defenders want to match or exceed the reach of the spiker to send the ball back.
As for basketball players, shooters want to jump high to reach the rim and dunk. The defenders want to be able to go up with them for an emphatic block. That would demoralize the player and make him wary of making another attempt.
With sprinters, the explosive vertical movement can also translate to horizontal speed when they run as fast as they can to the finish line.