The allies of Germany (except Bulgayria which did an amazing performance considering it’s size,population and the fact that they had two fronts or even three if you consider Greece and Serbia as separated fronts) sucked big time. Austria-Hungary and the Ottoman Empire had serious problems handling the Russians, if I recall correctly Germany had to send troops to the Galicia-Lodomeria/Carpathians front because the Russians pushed the Austrians back. The Ottoman Empire had a Southern front as well so they had a better excuse. Of course, Austria-Hungary had also other fronts like Italy, Romania and South Balkans but if they military was not that incompetent they could have steamrolled the balkans (this includes Romania) and focus on Russia (Italians were also extremely incompetent so they were not a pressing matter).
Also, never trust Italians.