The first thing warm-ups can do is promote dynamic flexibility through exaggerated range of motion activities. Second, we can teach basic movement technique via the warm up (think A-skips and B-skips for speed development; or cariocas for agility). Third, and a super advantage in the team setting, is the workout can be used to set the tone and energy for the proceeding session.
As coaches, we owe our athletes a great warm-up.
Team setting or not, the ultimate purpose of the warm-up is to prepare the body for exercise via elevating body temperature, increasing blood flow, and increasing heart rate. Warm-ups can also have the added benefit of reducing the severity of injuries sustained while performing.
Your athletes require a well-designed and thought out warm-up just as much as they do a sound training program. As their trusted coaches, the responsibility is on us to deliver that expertise.