I have played 3 as the Soviet(well, 2 plus a current one that is in mid 42) and 3 as the German..all against AI.
All three of the ones I played as the German against AI, I lost, but to be honest, 1 of them I lost by quitting.
All three I have played as the Russian, again, against AI, I either won, or am winning the current one. I have not used the "run away" against the computer, except to the better terrain along the major rivers. In all of them I retreated to those rivers, losing my share along the way, but held at the rivers except where I allowed a 'hole' to develop, and then closed the hole once the AI had pushed through several divisions, cut them off, destroy them, rinse, repeat.
I won by early offense however...from looking at how that developed, I am almost positive had I run away and given up half of my country early on, there is no way I would have won, at least, as early as I did.