The thing about that game is most people who haven't been long time Hockey fans, especially international hockey don't understand just how big an upset that really was. I can't remember who but one sportscaster at the time compared that win to a Canadian college team beating the Pittsburgh Steelers and that's pretty accurate.
The Red Army team was made up of players from the whole soviet union not just Russia, and they played together 11 months out of the year. Think the 92' USA dream team, except imagine if they played and practiced together for years. The U.S. wasn't know for producing hockey players. In the 70s US players made up less then 3% of the NHL. Even today less then 25% of the players in the NHL are from the U.S.