I've played this game solo many times this week. I noticed the Soviets losing when a heavy Panzer force is set up on the southern hexes. I kept a few up north but most of the heavies in the South in the first rows of hexes. It still wasn't super easy taking Moscow and holding it. I held only 3 hexes across the river at games end, Moscow and the hexes north of it. I even kept playing after the Germans won just to see and the Soviets eventually retake Moscow back but lost it again in a few turns. The Panzer divisions can gain a lot of ground quickly and can bypass or surround Soviet units trying to retreat. Try this strategy if you find the Soviets winning most games.