Stalin had purged the Soviet Army of its best Generals in purges of the late 1930s. Stalin had to bring back the survivors from Siberia to defeat the Germans outside of Moscow (and never really trusted them and the Generals distrusted Stalin so the Germans refused to be to imaginative when it came to tactics, less Stalin decided the planner of the maneuver was less important then the Generals who carried it out, thus the tendency of the Soviet Army to attack head on, even when the flacks of the German Army were open).
Second, What Stalin did in June 1941 makes no sense. The Traditional interpretation is Stalin moved his troops up from their old defensive line along the old border with Poland to the new border with Germany and thus easy for the Germans to surround and defeat. Worse, Stalin had moved up the supplies for those troops, so when the Germans invaded those supplies fell to the Germans.
An Alternative theory is Stalin was planning to invade himself, thus the troops were on the border with their supplies right behind them, as is needed if you are going to attack. Hitler's Chief of Staff, General Jodl stated during the Nuremberg trials that all he was doing was attacking Russia before Russia attacked Germany. In 1946 this defense was laughed at, but more recent records indicate they may be some truth to it,. In fact that the Germans hit the Russian Army was the Russia Army was about to attack would explain how effective that attack was. Most armies set to attack have a hard time adjusting to defense, mostly do to the location of their supplies. An Attacking army wants the supplies right behind them, so they do NOT outrun them to quickly. A Defensive Army wants them further back, so they can fall back on them. I hate to say this, but how far the German went in 1941 leads me to believe, the Germans hit an army that was about to attack and thus NOT set up for defense.
In any case, the fault lays with Stalin for the massive defeat of the Russian Army in 1941. By 1942 the situation had changed and even German long term planning showed the Russian winning the war (the big issue in 1942 was who would take Berlin? The Western Allies or the Russians?, thus Germany did no long term plans after 1942, Hitler disliked the results).
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