Always the most frustrating part of straight up figures like this. People latch onto them without much thought and then you get troglodytes who will argue the players your talking about should just play for countries they were born in despite zero connection there.these percentages don't tell half the story.
Players like Shields are a problem and we should curtail that level of nonsense but we shouldn't be consigning Underhill to being America's only good player just to circumstances of where he was born.