Reasons why Germany lost the war in the east:
Logistics, logistics, logistics: the German military spared scant energy and resources on logistics - reliable trucks in appropriate (read: American) numbers, repairing/adapting the Russian railroads and rolling stock, real airlift capability. No doubt a combination of the unsexy and bourgeois nature of the field as well as cosmic certainty that the war would be a short one, even though pre-Barbarossa logistical wargames predicted halts in the offensives due to an inability to move supplies to the front. This unwillingness to waste resources on anything except the pointy end of the military ended up hurting the Germans throughout the campaigns in the east. This is also the reason why proposals for sending some greater increment of the military against Moscow are ludicrous - sending twice as many soldiers is of no benefit if only the same quantity of bullets, shells, rations and gasoline are being sent to the front. Similarly, sending just mobile units compounds the logistical burden while leaving flanks wide open for being cut-off.
War production: on the face of it, Germany should have creamed the Soviet Union from a production point of view. Germany was in 1939 had the second highest war-making potential in the world (lagging well behind the US, the leader). The Soviet Union was number three. (UK was #4) By the end of 1941 the Germans had scooped up a huge chunk of Russia’s land, people, and infrastructure. And this is added to the fact that all of Europe’s population and factories were effectively at Germany’s disposal. But Germany had bass-ackwards production systems and no serious attempt was made at rationalizing the system until 1943 under Speer.
Occupation policies: Germany managed to piss of just about everyone under their thumb. It boggles the mind that they were able to get just about zero traction from their crusade against Russia/bolshevism. Add to that the fact that their actions/policies left no doubt that the goal was to screw the occupied territories for Germany’s benefit and you end up with a sizeable chunk of Europe’s productive potiential going to waste. (Similarly Nazi family values ideals prevented utilization of German women in factories).
Overconfidence/refusal to learn: The Germans never seemed to grasp that all of the tactics that won them their empire were no longer terribly effective. Their opponents had learned too many bloody lessons and would no longer cooperate. At the same time their absolute knowledge of the superiority of their own intelligence and intelligence services left them blind to the actual superiority of Russian operational deception (and allied cryptographic superiority in general).
Declaring war on the US: This had two effects. First, it guaranteed a substantial diversion of resources away from the eastern front (whether mobile forces to the Med, numbers of divisions to Norway, Italy, and France, or the preponderance of fighter aircraft and vast quantities of AA to the fatherland). While the majority of forces still fought in the east, efforts were now fractured and the few major offensives in the west saw the annhilation of mobile forces more useful for defense in the east. The second major effect was lend lease. While substantial numbers of aircraft and tanks were contributed, even more important were the immense quantities of rolling stock, railroad engines, aviation fuel, radios, food, explosives, raw materials, and trucks trucks trucks trucks trucks. The fact that such vast quantities of material were available freed up Soviet industry for the production of aircraft, artillery, and tanks. [For the purposes of this paragraph I do not wish to denigrate the contributions of the UK in both the “distraction from the Ostfront” sense and in the lend lease arena (where the UK sent materials they badly needed themselves to shore up the USSR). The US multiplied the ability of the overstretched commonwealth countries in both these arenas.]
Naziism and incentives: Both the Soviet Union and the USA were able to wildly increase production over the course of the war. In the US a combination of underutilization of pre-war capacity with patriotism and the potential for huge profits did the trick. In the Soviet Union hunger and hatred worked wonders. In both cases the bulk of the workforces could hardly be considered skilled before the war. In Germany there was no equivalent success motivation-wise. When Hitler called for a quadrupling of aircraft production industry leaders said it couldn’t be done. IN the US when FDR called for 50k aircraft to be produced the following year capitalists just saw the dollar signs and the race was won.
Naziism and government: Hitler used divide and conquer policies amongst his subordinates. There would always be pointless divisions within the government because Hitler needed them to prevent any of his lieutenants from getting too powerful. The Nazis knew the war was not terribly popular (although the one-sided victories changed that). As a result many policies were based on the necessity for a short war, so that consumer goods production could continue. Again, whenever faced with unrest from Germans the Nazi government seemed far less effective at changing opinion to favor itself than either the USSR or western allies, and gave in.
Naziism and Ideology: Because ideology trumped all else, there was a tendency to supress any unpleasant facts or realities (eclipsed only by the Japanese). Unsuccessful or unenthusiastic generals were sacked. The freedom of action of local commanders was restricted. Resources were wasted on the Final Solution, the resettlement of the Volksdeutsch, and other ideological projects, resources that could have been used to some effect on the war effort.
I do not think that a 1940’s era Russo-German conflict is of necessity a one-sided Russian victory. I just don’t think that Nazi Germany could remain Nazi Germany and still win. To be sure, a negotiated peace was certainly possible until late in '44, and a less self-deceived Hitler may have obtained one.
