PzJg, the Kampfgrupp is no more than a reorganisation of different routed units in one fighting bigger unit, combining Luftwaffe unit, different infantry units (SS, Wermarcht) and Kriegmarine and to make it as a fighting unit. It is the Corps d’Armee from Napoleon, modernised. What was really surprising is the speed the Germans succeeded to do it.
I don’t agree with your analyse about the use of the Blitzkrieg concept by the allies. They allies didn’t plan to cut the German and surrounding them. It happened but it is another concept, it is the concept of the battles of opportunity (developed by the Red Army). Falaise could be a good example of it. You react to the situation and play on the enemy mistakes.
Market Garden was a success because paratroopers can’t defeat Armoured Division. I tried to explain this many times to friends (paratroopers) but they never get the point. A tank goes faster, had bigger weapons, etc… So Market Garden is an example of how not to use paratroopers and airborne divisions, unless you provide them adequate support.
Question: Are you sure it was Manstein in command and not Model? For what I know Manstein was dismissed in March 1944.
And if you study Patton tactic, you will see he was as much flexible as his german counterparts.