One of the peculiarities of this game, similar to WITP, is that one side can tinker with its OOB or equipment quite a lot (the soviets here, just as the Japs can tinker with their aircraft production in WITP), while the other is stuck with its historical OOB and equipment (The allies in WITP, here the Germans).
This unbalance can be frustrating to players. In WITP it leads to good japanese "optimizator style" players managing to outrproduce the allies in terms of airframes. But at least it's the "weaker" side that gets this boost. Here it can be doubly frustrating for the Germans from 42 on to see the Soviets massing guars units, rifle and tank corps, artillery divisions, shock armies, in the way of their choosing (to some extent at least), while they are stuck with their OOB and the exact type of units equiped with Tigers or other equipment.
It means that whether the German player plays well or not, has secured a solid capturing of factories and population and ressource centers or others, has managed to limit his losses, he cannot build upon this to reinforce his troops beyond the strictly historical setting.
I would advocate a certain leeway. Indeed, not transforming this game in a free for all what if, but allowing the german player to create more support units for example, would be a good way. If a german player has conserved his forces well, and through limited losses (no Uranus, no Zitadell, etc...) built up solid pools of Tigers, Panthers or others, he should be able to use them, of course whithin roughly plausible limits.
Adieu Ô Dieu odieux... signé Adam