I've been watching the tournament from inside and outside for many years, and there are a few observations I've learned that are worth repeating:
1) In a short tournament, you almost always need your goaltending to be elite to have a shot at it. Knight tossed a shoutout in the biggest game, and you cannot ask more from any goalie than to keep the opposing pucks out of the net. When skaters are confident in their goaltending, they are free to be more creative and dynamic to make plays.
2) Your 19-year olds not only need to be great players, but need to culture setters for the rest of the team to follow. Team USA's 19 year olds got the job done and you could see the confidence rubbing off on the younger guys. Confidence is critical, and the 19-year-olds are the ones who impart it. Most 17-18 year olds are often amazed at the major difference in game speed at this tournament from the level where they are playing normally, and that speed difference can really mess with younger players who haven't seen it before. Faster reads-and reactions force players to make more decisions, more quickly, so having great "hockey sense" is what coaches look for as highly as skill when picking guys, and following the 19-year-olds examples are usually how younger players adjust.
3) In one game knock-outs, a team's reloads, gap control, shot blocking and face-off wins take on outsized importance, often determining the kind of time and space that determines scoring opportunities for or against. Film sessions spend a lot of time on player roles as it relates to puck possession. These situations vary by national playing style, too.
4) Having high draft picks is very helpful, as elite skill can be difference makers when match-ups happen when with best-on-best, as you saw when Team USA top guys scored on Canada's top guys. But non-skilled self motivation, such as keeping your feet moving, having guts to get to dirty areas and willingness to do the little things are what elevates even the highly-skilled players over other highly skilled players, rather than just applying more skill.
5) Over the course of a tournament, your team's third line's effectiveness often can become the difference maker in advancing. If you can get offensive production from third line guys, that frees pressure on the top 6. Team USA's third line was really effective keeping pucks deep, drawing penalties, and getting to the dirty areas.