We have to disagree here. Some things can be determined pretty exactly based on the "what-if" approach, simply by adding or subtracting something from the equation of history. Example......"what-if" von Manstein hadn't pushed his plan for the attack on France, but, instead, had been a good little German officer and shut up when his superiors told him to? In that case you'd have had a rehash of the Schlieffen Plan, which was exactly what the Allies had laid plans to counter.
Or "what-if" the US dive bomber attack on the Japanese carriers at Midway had been 5 or 10 minutes later? In such case the Japanese would have been back in defense formation, been clearing their decks and their fighter cover would have regained altitude and been in position to counter the attack.
And you're pursuing a false thesis when you say that "To clasify a battle as decisive you just have to look at its immediate consequences on the current events at stake at that particular time."
For example you don't object to Salamis as decisive, yet the immediate results of Salamis caused nothing but what the Persians intended as a temporary withdrawal, through the disruption caused by their supply line becoming insecure; their resources were such as to allow them to replace their fleet losses in a short time. It was Plataea that actually ended the Persian invasion, and that battle could easily have gone against the Greeks had the Persian commander not been killed--and the Greeks couldn't have replaced their losses there, had they lost. By your own definition it was Plataea that was decisive, and not Salamis.....and how did either of them affect anything more than locally--by your definition--when something like the Teutoberger Wald didn't?
Or take a later decisive battle.....Pearl Harbor. Its immediate military consequences gave the Japanese command of the Pacific and the far east.....but its longterm consequences were the utter destruction of the Japanese Empire AND the assured destruction of the Third Reich. More than Midway it was strategically decisive, as few battles have been.
Or take the success of Fall Gelb.....its immediate consequences were a disaster for the Allies.....the destruction of their most mobile forces thru encirclement and the evacuation of the BEF minus most of its equipment, followed by the complete defeat of the French Army in Fall Rot, which was followed by the capitulation of France. Looks pretty decisive in its immediate effects, doesn't it?
But appearances are deceiving.....it was OPERATIONALLY decisive, but wasn't decisive in the grand strategical sense. And the grand strategical sense is how one rates "decisive" battles. Fall Gelb was a strategic dead end for Germany. It was intended to end the war since Germany needed a short war due to economic reasons, but it only ended a phase of the war.
Likewise, Stalingrad wasn't decisive in the grand strategical sense.....all it did was inflict a major tactical defeat on Germany. It took Kursk to inflict a grand strategical defeat, because it used up the German operational reserves and led directly to Germany's permanent loss of the strategical initiative on the Eastern Front.
You're looking at the trees here, and ignoring the forest. Yet for determing a grand strategically decisive battle you HAVE to look at the forest and ignore the trees.
You say that certain of the battles I listed as decisive were not, that they further had only local effect. I disagree. The Teutoberger Wald--the "Varus Disaster", as the Romans called it--affected the entire Western World; is that "local effect"? In turn, longterm, it affected the entire history of the planet by leading to the eventual overrunning of the Western part of the Roman Empire, thus causing the Dark Ages, which led to the formation of modern Europe, which led to imperialism and the domination of most of the world by European nations and their cultures.
With some battles it's easy to determine their effects.....with others you HAVE to look longterm to see what the effects eventually were.
I could go on in a lot more depth and detail, but the above ought to suffice.....as I said in my initial post, what is decisive is subjective.....if you take a hundred people and the hundred make a list of decisive battles, you'll always find that while some battles are agreed upon as decisive, the lists will always be different.