There are units that exploit the weaknesses of the US and close the gap early-mid game by increasing their losses. Obviously the US is strong early game and weak late game compared to Ost.
So far I got:
Sniper, 222, Assault grens, Stug III E
Sniper?
Meet Mechanized Doc for the Americans with the Steroid Jeep, which counters that nicely. Or just Spam riflez, flank sniper, insta-dead. Assault Grens? Meet AA Halftrack. StugE? Meet a Sherman.
US has, and always will dominate early game no matter what you try. Late game is where it is only weak and the OKW/Ostheer stronk.