A stacked battle is one where one side has more advantages. I bring up the Eastern front because Germany had certain things that gave them the combat edge in a lot of situations. They always had the biggest guns right up till the end when they couldn't afford them, they made their tanks small, fast, and gave them radios which made them much more deadly against the calvary tank doctrine, they invented the assault rifle, they had a dominant airforce, they had homogenous culture and an entire economy devoted solely to war and a relative lack of ethics. These are things that make an army good at killing but not necessarily good at surviving.

Compared to the Russian which had less in the way of electronics that the average soldier saw, a large focus on compromises for mass production, a fairly diverse set of peoples and a very spread-out economy with a young industrial sector. Soviet doctrine wasn't the best at conserving lives either.