During hot weather, hydration (drinking water or a sports drink) is VERY important and can make a big difference in the second half of a soccer game. I think it can be worth a goal or two. Hydration is also a VERY important health issue for soccer players - dehydration (the lack of adequate water in the body) is a serious matter and can cause illness or stroke. Every soccer coach and parent needs to be concerned about proper hydration and how to avoid dehydration. Hydration is a subject on which there is a great deal of misunderstanding, misinformation and disagreement, yet it's very important. It's both a health issue and a performance issue. No soccer coach wants to allow a player to become ill due to the coach's unintentional neglect or ignorance, but that is what could easily happen if dehydration occurs. Energy replacement isn't a health issue, but it is a performance issue. Soccer coaches who understand hydration and the need for energy replacement, and who take some simple steps, will give their team an advantage over teams that don't, assuming they are fairly evenly matched (phrased differently, if the opposing coach is proactive about hydration and energy replacement and you aren't, then your team is at a disadvantage). You can't control a lot of things, but this is one thing you can control that can make a difference between winning and losing, and it's something you should do for health and safety reasons and for the good of your players.