Found a blog about tactics that is a pretty good read. He did not cover the 2nd US game that I can find, but two articles do cover the US team.

http://www.zonalmarking.net/2010/06/...tic/#more-3503

This gentleman explains his theory about the early goal by England. That Oguchi Onyewu has a habit of being pulled out of the defensive line (very close to the explanation provided earlier by wootah). However, he faults Onyewu for this, saying he is too easily drawn from his position (he refers to it as dragged toward the ball), leaving too much open area for his partners to cover. The point of their preview article (link below) is that this was happening in the preliminary rounds as well, pointing to a serious problem in the US defense.

He has a few nice diagrammed photos showing this happening elsewhere in that match, though it did not cost them any goals in those cases. The second diagram shows wootah's point about covering for the middle field teammate, but also reveals the problem of needing your teammate to come into the middle to defend the zone that you just abandoned. It leaves the wide guy completely wide open.

Here they cover the US pre-tournament: http://www.zonalmarking.net/2010/06/...-2010-tactics/