Since the World Cup Bob Bradley has been experimenting with a 4-5-1 formation. Despite Altidore being a poor striker and the terible results the formation has produced, many people have justified giving the formation a shot because they believe the US has great depth in midfield.
After watching the USA-Argentina match, it has become painfully obvious that this belief is false, and the US actually lacks depth at midfield. While Landon Donovan and Clint Dempsey are no doubt the teams best players, they are forced to play out wide because the US doesn't have a single wide player. While they are good as wide players, they are a much bigger attacking threat if they could play up the middle.
The US started the match with Jermaine Jones and Michael Bradley as their holding midfielders. Donovan and Dempsey were further up the field as attackers, but in between the two of them was Maurice Edu, a holding midfielder who is actually playing as a central defender for his club team. Edu looked completely lost when playing as an attacking midfielder, and looked much better, when he moved next to Bradley in the holding role in the second half.
The positon Edu was playing would have been a natural position for Stuart Holden. However Holden will miss the next six months now with an injury, forcing the US to use Edu out of position. After Edu, the US has Benny Feilhaber, who was also injured for the Argentina match. After Feilhaber though, the US is left with a bunch of young untested players, players that Bradley did not have faith in using against Argentina.
The US actually has a lack of midfield options, forcing Donovan and Dempsey to play positions where they aren't as effective. As soon as one injury strikes as it just did, we end up seeing a US midfield that struggles to gain and keep possesion of the ball.