That is very hard to say, but i do think if Hitler had a hands off approach and allowed his Generals to do what they were trained to do then yes, i believe the Soviets would have certainly have lost the war, but having said that i also believe that there were several worry warts in the German General ranks Rundstedt was one of the worse, it was he that gave the gloomy report that led to the eventual escape of the BEF and the 1st French Army at Dunkerque.

But in the end Hitler ignored Rundtstedt, and that extended the war by at least two years, but in the end Hitler and Hitler alone cost Germany victory, he was the best weapon the Allies had.