[grognard]

I choose a combination, because a) the russians had learned from the earlier fighting, b) they did have numerical superiority, c)the Germans were worn down and without some of their best commanders, e.g. Kleist & Manstein and d)Hitler interfered too much, and the Russian skills included deception so the Germans often did not know where the next blow was falling, e.g. when Bagration hit, the Germans were expecting an attack further south, etc.