LM:-
the failure to capitalise on the German total commitment to Poland in the autumn of 1939 is seen as a mistake. In Jodl's evidence at Nuremberg he points out the German weakness in the west at that time.
So the reason that he was hung as a War Criminal was because Britain and France botched their chance to stop Hitler in 1939? It was he and the rest of the German High Command who failed to stop Hitler, and botched it when a few of them did finally get round to trying to rid the World of him. It was he who signed the Commando Order to summarily execute uniformed Commandos when captured, and he was rightly convicted at Nuremberg.
He may have thought that a joint aggressive operation by Britain and France in 1939 could have been successful, but I would very much beg to differ and can only echo the view of George VI after the fall of France, "Thank God we are now alone"!