re: 1980 USA Hockey Team - What made them successful?

The beginning of the movie actually did a pretty good job of explaining it.

A few things at work. The Soviets had a degree of Tyson mystique to them in that they beat many opponents before the puck was even dropped. Coach Brooks had a plan to get his team to buy in to respecting the opponent but not fearing them.

Second, many teams basically tried to bunker against the Soviets for a whole host of reasons, talent gap, Soviets were highly skilled on offense, their goaltender was unbelievable. The Soviets destroyed teams that bunkered. Hell, they absolutely demolished the NHL all stars. Coach Brooks was going to attack them and make them play both ends of the ice.

Third, most teams are structured around selecting members based on taking the absolute best hockey players like if you were drafting. Coach Brooks selected his team based on tasks he wanted them to do. It is unconventional and very hard to justify. I think Brooks was selected despite pitching this because coaching that team was seen as a no hope situation with the USSR in the field.

As to what they did on the ice that made them successful, I can't give you too much specific insight, but it was based on passing and an attacking style that, as you mentioned, was not really all that prevalent, especially against the Soviets who punished mistakes with their gaudy talent.