Well, that the Flyers "gooned it up" in this game has always been a bit of a misrepresentation. There were no fights, for one. Now they *did* hit hard--and by today's standards perhaps a bit too hard. But not by 1970s standards. What really won that game for the Flyers was coaching. Shero saw a flaw in their system (just as he'd done vs Boston in 1974, when he go Orr to carry the puck more, and tired him out). He knew the Russians liked to skake the puck into the zone, so he set 4 across the blue line and forced them to dump and chase if they wanted to get the puck into the attack zone. That wasn't their style and they had a hard time adjusting. Of course, the smaller dimensions of NHL rinks compared to European rinks made this tactic easier. Of course the Russians were not used to the hitting and I 'm sure the crowd was intimidating too. But Shero's study of the game was what made the difference. He'd even gone to Russia on his own to learn from them.
Tretiak, however, was an amazing keeper. Not having him playing the second and third periods was a major factor in the US win in 1980. I got to see him play (on TV) in the 1978 World Championships final vs the Czechs in Prague (as I was living in Germany at the time--PSU exchange). A hugely hostile crowd, and the Czechs were buzzing from the start. He stoned them cold--and the Soviets won.
according to the film "Red Army", the Russians refused to go back on the ice after the first period against the Flyers. Until they were told they wouldn't get paid if they didn't.
Capitalism at it's finest.