Jazzman, I am not a doctor and don't pretend to be one, but your comment about "nothing hydrates better than water" is somewhat irresponsible and a little incorrect.
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For years, heath care and fitness professionals have stressed the importance of fluid intake and replacement in preventing dehydration. Therefore, most health conscience individuals are educated about dehydration and cases of dehydration have decreased in recent years. Yet, in some cases, people may take dehydration prevention a bit too far and unintentionally drink too much water. Drinking an excessive surplus of water can lead to over-hydration or hyponatremia. Although hyponatremia is rare and seen primarily in serious endurance athletes, such as marathon runners, it can be dangerous and fitness enthusiasts should be aware of the condition.
The medical dictionary defines hyponatremia as an abnormally low concentration of sodium in the blood. Hyponatremia is also known as “water intoxication.” Sodium (salt and chloride) is an electrolyte, which helps the body distribute water. This is essential for water balance and for your muscles and organs to function effectively. Electrolytes are lost through sweat. When exercising, our body temperature rises and we sweat to keep cool. The more we sweat, the more sodium lost. Sweat loss varies from as little as 16 ounces to over three quarts during each hour of exercise (Gatorade Sports and Science Institute). For this reason, it is important to replace lost body fluids during and after exercise. To completely replace these fluids, you must not only replace water, but also sodium and chloride. Those who consume excessive amounts of water after exercise can further deplete sodium and chloride levels, leading to electrolyte depletion and possibly over-hydration
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Without sodium in your body, your body cannot absorb water the way it needs to. Last year a Fraternity decided to be funny and at initiations they had the kids drink water instead of beer or whisky, thinking they would be ok. Well, one kid died of hyponatremia, he basically drowned himself in water.
Gatorade isn't just some sugary drink designed to simply taste better, it was developed by scientists at the University of Florida in a laboratory to solve this very problem of hydration and sodium replacement.
While hyponatremia usually only occurs in marathon runners or long distance event athletes (cyclists, triathalon), I would imagine practicing for 3 or 4 hours in the middle of texas or Florida in August or September would suffice.
If you eat properly before a game, there should be enough sodium in your body and water will usually suffice for a game, but some games are hotter and longer than others and some and not all athletes will have their bodies respond the same way.