It is certainly a generalization, and no, I can't prove it, but I think one obvious reason foreigners are turning America into a second-class sports power is that our children are being brought up (on videotape instruction) to believe that sport must be contested under carefully controlled conditions. So they invariably whine and stumble when that isn't the case, which it usually isn't.
It's the same in politics, where name-recognition primaries are considered the fairest way to select our leaders. Smoke-filled rooms have come to have the same bad connotation as mud. But I suspect we might have been the better for it when we were jammed into uncomfortable little gyms (or little smoke-filled rooms), when games were played with nooks and crannies, and people got dirty. We knew each other better then. We weren't just watching. We were the home court advantage.