How did Nazi Germany have such a weak army during World War II?

they had a large army, it was the lost nut that caused the problem that the Bavarian spear Cpl Hitler caused to fail when he was told in 1940 that Germany was running out of fuel

and the Man in charge sacrifices 1,000,000 men and all his Team in Stalingrad, then heads to Moscow and then changes his mind when the first attack should have been the oil fields

Hitler had no idea what he was doing.

and on December 27, 1944 Germany ran out of fuel