Well the AI has unlimited movement points, so can re set its defensive line while the human player has to play by the mps of a unit, (the AI air routine will self destroy the LW by running it into the ground by over use, and as it flys day and night 7 days week in all weathers, its operational losses are always high, as USSR it can afford those losses, while the LW cannot) so it appears to defend better by cheating, destroying its own air assets, a unit in AGS during the Soviet turn can re set to being in AGN for the next Axis turn. Against the Axis AI you can be in Berlin late 42 early 43 nine games out of 10, with a field army of 7 to 8 million, so i dont find it interesting to play as SU in single player. Axis AI will under perform relative to a human in every respect, its T1 attacks will be 3200-4200 range while a human can top 6000 and suffer half the AI losses to inflict that. Ground war is very similar, its T1 pockets are not good and can be broken as SU, and 00s of 000s dont become pows, while a humans pockets usually hold and they do. To get the best out of the game engine, playing as Axis is a challenge to get a win, while playing as USSR is when do i want to win.