US certainly seems to step up when they are the underdog and gets tight when they are favored to win. It was clear going in that the US needed someone to step up on offense and could not rely on Pulisic alone. US has only scored twice in three games.
Of course, the good news is that the US only gave up one goal and it was on a PK for a stupid foul (stupid meaning the US defender had no reason to try to make a tackle inside the box with Bale facing away from the goal).
But the US defense cannot carry the team through the knockouts. Offense needs to pic up the pace and players need to finish.