It seems a little wierd that the German's losses were proportioally so low. Of course it probably has something to do with the Soviet strategy of throwing men at the enemy. It's sad to think that so many died because their "commanders" were such idiots. It's very similar to WWI, well I suppose its the same in all wars.
First of all, add in the client states, puppets and allies of Germany on the eastern front and the casualty rate isn't THAT extremely different anymore. In addition you have to remember that the Soviets had extreme losses in the opening months of Barbarossa. Look up the Minsk encirclement as an example. It wasn't so much down to Soviet small unit tactics or human wave attacks, it was more to operational losses.
Also, most casualty comparisions you see have POW's who died in captivity included. Now we all know the Germans didn't threat captured Soviets very well. If you ONLY go with KIA/MIA's without POW's then the difference really isn't that high anymore. Numbers taken from Wikifail since I'm too lazy to go with anything else atm.
Total Axis KIA/MIA Eastern Front:
4,428,000+
Total Soviet KIA/MIA Eastern Front:
6,927,204+ (you have to add Partisans though)
In addition, since Germany was on the offensive during most major breakthroughs involving extreme casualties for both sides you can expect that the ration of KIA-WIA will be higher for the Soviets than the Germans. So the total wounded+dead toll would be nearly equal.
Remember, Operational losses will always be far more severe for the defender than for the attacker. Think for instance of Normandy. While the Germans often had the tactical advantage due to favourable defensive terrain (bocage) and had dug in positions and pre-registered artillery points, they were on an operational disadvantage. Generally if an attacker sustains a loss-rate of 30% for a company, Battalion or Division they'll usually be able to pull it back. The defender can't really do this and once the attacker breaks through the losses in men and material will always be far higher for the defender than for the attacker. Think of all the rear echelon non-fighting units suddenly finding themselves under fire and overrun by enemy tanks. THIS is where the real losses in any operation are and which is why the defender has nearly always far more severe losses when the attacker achieves a decisive breakthrough.