"When two NHL hockey players collide, their pads and body tissues can absorb enough energy to power a 100-watt light bulb for a minute and a half. During the 60 minutes of a hockey game, players can burn 6,000 calories and lose up to 15 pounds."
I know whenever I play goalie in my roller or ice leagues that I lose an average of 6-8 pounds of sweat per game. Drink a lot of fluids before and after every game. So those numbers you gave don't really surprise me at all.