It was not so much that Austria had a bad military per se but that they were in all over their heads in a war they couldn't fight and fell victims to several blunders that cost them hundreds of thousands of men. They couldn't take Serbia out without German support, they were nearly overrun by Russia in Galicia several times, Russian offensives that were only stopped by massive German interventions. The only front they did well throughout was Italy, though Italy, like Austria, was equally in a war it was illequipped to fight as both countries were in industry, manpower or economy not en par with powers like Germany, France, Britain or even Russia.