"...the art of manoeuvering armies...an art which none may master by the light of nature. but to which, if he is to attain success, a man must serve a long apprenticeship." -- G.F.R. Henderson
Just got done with Autumn for Barbarossa, nice little SCS game....I don't see how the Germans can win if they still have to slog through the Russians to take Smolensk after the bulk of their Panzers are withdrawn. This seriously weakened the German drive making it almost impossible to achieve many new objectives. I felt the game was basically over at that point with a few turns left.
You got the point of the situation--it's nearly impossible to achieve many new objectives after the Panzers are withdrawn. But the Germans can't slog through the Russians. They have to create situations where the Russians are defending many points and--therefore--have to spread out, usually in hedgehogs built around clusters of VP locations. Then the German picks the weakest points and mass against them to breakthrough and breakout....
Games on the Smolensk campaign are very different as the German usually has to put his mechanized/motorized fangs out--far out--well beyond what looks to be safe and far beyond supporting infantry. The goal is to take what the German needs to win overall at the front and leave some Soviet forces in the rear area, even if sitting on some of those VP locations. When the panzers leave, the German player must be judicious enough to allocate force to both hold what was taken in the easternmost zone, yet still have enough in the rear area to finish off those Soviet remain-behind forces on VP locations to eke out a win on the last turns.
It takes a lot of practice for the German to learn how to keep up a constant tempo of overruns in the movement phase, attacks in the combat phase, overruns in the mech movement phase to ensure he's threatening more places than the Soviet player can adequately defend. The Soviet player can't defend everything, so his operations must be aimed at reducing German options to the fewest predictable ones, ones he can gum up in good defensive terrain. That also takes a lot of practice.
A lot more needs to be written about this game and I'm sure you'll get a lot of good ideas once review pieces and session reports come out on BGG (yes, I'm writing up some!)