Stalin is rightly viewed as a tyrant but massively undervalued from a leadership perspective.
I don't think he was any better or worse than Hitler by and large. Stalin eventually trusted his generals. What won that war for them was the hard Russian culture.
99% of wars ever fought is always one side overwhelmingly more powerful than the other. And that makes sense, otherwise wars would never be fought. However, you had the coalition wars of the 18th century, but those were more or less teams fighting one another for specific goals. Of the epic titanic clashes the last thousand years, they've involved to some degree the Russian/ Asian steppe.
Mongols come to mind first and foremost but it was a group out of more of less Siberia fighting a lord of the rings titanic war with the Chinese for nearly 75 years. An amazing story you never hear about were the Mongols demanding the surrender of the Russian princes, and to a man they said no and I believe all were killed in a single battle of two. Then you had the invasions and bloodiest war of the 1700's by Frederick the Great, you had the Napoleonic Wars, you had the Germans in WW1 & 2.
I think the easiest place to invade geographically is Russia. It's wide and open during the spring and summer. And I think the group of people that have inhabited that area for so many years are the hardest people on the planet. Because they haven't been dislodged. Stalin didn't help those people win the war anymore than the fact they are fanatical and willing to fight like no one else on the planet.
WW3 to some degree, after the bombs have fallen, will be fought on the Russian Steppe.