USA: Jurgen Klinsmann battling to find the right formation

Which formation is right for the United States? 

It is a dilemma that Bob Bradley faced during his tenure as head coach and now follows his successor Jurgen Klinsmann.

After having some success with a 4-3-3, Klinsmann switched to a 4-4-2 against Canada hoping that the system would take advantage of having Clint Dempsey and Landon Donovan together on the pitch. The results were mixed at best.