Blitzkrieg has been around for centuries, it's the exact same tactics as used by Napoleon (penetrate a single point, encircle, destroy) but with more advanced technology. The big thing that gave the Wehrmacht a massive advantage at the start of the war was inclusion of radios in Panzers to allow for incredibly efficient coordination. That, and the old Prussian ethos of mission tactics, with junior officers taking the initiative and not sticking to rigid battle plans. Blitzkrieg works fine in a relatively small theatre of war (Poland, France, etc.), but because of the vast distances involved they found it very difficult to implement successfully in the East.