were true, which clearly is not.”
Ummmh.... NO, IT WAS NOT, the Germans MAINTAINED THE Strategic OFFENSIVE INITIATIVE for another 6 months after the Stalingrad lines stabilized.
That initiative was lost at Kursk, AND in Sicily.
Kursk began on July 4, the Invasion of Sicily began on July 9. Air and Ground assets, (especially fighters and Tac bombers), that were to support the 2nd and 3rd phases of the Kursk Offensive, Operation Citadel, were diverted to Southern Italy.
40% of the German Air Groups committed to Citadel (3 entire Air Corps) were diverted to Sicily.
Until that point, the Germans had been able to maintain strategic inititaive in the east. After that, it became a losing game.
Guderian acknowledged this point very clearly in his book. The losses of Stalingrad were made good, but after Kursk, they could no longer be made whole.