That four-run gap is entirely comprised of unearned runs as the USA has made three errors.
As I type that, Hiroyuki Nakajimi lifts a Scot Shields pitch into shallow right. Adam Dunn crosses over, but decides, incorrectly, that it's in the gap and should be the center fielder's ball. He eases up and the ball rolls slowly to Shane Victorino as Ichiro Suzuki comes around to score all the way from first base.
A groundout then mercifully ends the inning.
Could things get worse for the USA? Well, Yu Darvish is coming in to try to close this game against Derek Jeter, Jimmy Rollins, and David Wright.