And we believed this turn around? When the senior Russian officers in question would have been the politically-savvy survivors of repeated Stalinist purges of the Red Army officer corp and thus HIGHLY averse to "defeatist" [e.g. appropriately fully-dimensional strategic] thinking?

I think it should be kept in mind that this latter-day rethinking by the above German officers was being done by a set of canny survivors who were well aware that their words were being used to "correct" the overall understanding of the war. So these individuals *may* have wanted to make themselves look better in hindsight. Generals who lose to a horde of untutored barbarians look a lot sillier than those who lose to a set of highly-skilled opponents.

I think the truth is somewhere in the middle. Enough skilled Russian officers survived the purges AND were lucky enough to be paired with political commissars realistic enough to avoid strict application of Party doctrine, thus allowing the Red Army to eventually take the offensive against a resource-starved Wehrmacht. But it was a near-run thing and I *strongly* doubt that it was the result of a reasoned overarching stategy on the part of the Russians.