Here is the unit comparison
The russians have 100% morale, going to have to analyse a battle with that. With thier 40-50 stacks
Morale from loans from other countries are around 30%
From the progress of battle it's hard to see what factor morale is playing
German
The German doctrine tree is exceptionally strong, particularly between 1937 and 1941. It has extremely high organisation, fast headquarters units, cheap tanks, and Breakthrough and Encirclement offensive combat events. Most of the benefits are achieved by 1940, giving early advantages.
Between 1939 and 1942 there are also cost savings on infantry and artillery; in 1943 these are switched to motorised and mechanised troops and self-propelled guns.
German doctrine is ideally suited to nations who are seeking to conduct rapid Blitzkrieg offensives. The high Organisation levels mean that German troops are very good at winning battles and sustained operations. The only disadvantage is that some other nations have better cost reductions, and defensive combat events are scarce.
USSR
The Soviet doctrine tree has low Organisation throughout but exceptional Morale. At every stage Soviet Morale is higher than any other type.
There are significant discounts to Infantry and Cavalry throughout, biggest in 1940-2. From 1942-3 onward there start to be big discounts on Motorised, Mechanized and Armoured units. HQs are slow and give virtually no Supply Efficiency bonus until 1943.
The combat events focus on Assaults and Counterattacks, which trade your manpower for enemy organisation.
Soviet doctrine suits nations which have plenty of Manpower to make lots of Infantry units which throw themselves at the enemy on the offensive or the defensive. The slow HQ speed means an operational attack is relatively slow and needs careful planning.