Warming up is important for performance and injury risk, it is a training factor we often neglect. Not only does it serve to prepare the body, but it also motivates mentally for the challenges of difficult drills and games ahead.
Plyometrics or "plyos" is an exercise used to increase your speed and strength, which is one of the most effective methods for building explosiveness. In other words, this form of training improves your ability to deliver maximum power in the shortest amount of time. It is for improving jump height, sprint and agility as well as improving your ability to coordinate movements. Perfect for jumping your highest for the perfect spike or receiving those difficult hard driven balls. Plyometric training will be the best way to improve these properties and is not limited to jumps.
Volleyball is a sport that requires strength because it is a sport of high intensity bursts with intervals of rest. Strength training is typically performed with an external load such as weights or other external resistance which causes changes in both the muscles and the nerves that supply the activated muscles. You do not get more muscles, but the capacity and size of the muscles are increased and the ability of the nerves to activate the muscles is improved. The result is increased muscle strength. Strength training also strengthens the tendons and bones and has a positive effect on the body's metabolism. If you neglect strength training then you might as well neglect plyometrics and your chance of being your best version of a volleyball player.