johnberardi.com has a wholllleeee section on nutrition as well as some pretty awesome free recipes for meals that will kick your body’s ass into nutrient heaven. As for your friend tell him to focus on carbs with a bit of protein.
Carbs are obviously for energy while the protein will start absorbing into the body while he’s playing so that by the time he eats after his muscles havn’t been screaming for protein to rebuild for two or three or however many hours.
Also water before the game is crucial. Not right before drink a gallon. Drink a few glasses in the hours going up to the game and a glass around the start. Drinking water during the game, although sometimes necessary is not something you want to be doing like a hot dog in the summer every time lines shift.
If you’re doing that you’re already well on your way or are dehydrated and you’ve lost. Sounds like a lot of over emphasis on water, but trust me it can make a big difference.