I freely admit that the Greek War of Independence is not one I've studied in any detail, but I still have to say that international intervention was decisive in resolving the conflict in the Greeks' favour.
The Battle of Navarino was the first official intervention, it's true, but European military advisers were training and leading Greek forces before then.
Navarino and the negotiations before and after it caused a significant halt to Ottoman military operations. Prior to then they had started achieving real successes in regaining control of territory.
And Navarino wasn't the end of outside intervention either. The threat of French military intervention caused the withdrawal and recall to Egypt of the substantial Egyptian army in the Peloponnese, depriving the Sultan of his most effective military force.
One also cannot overlook the Russian attacks against Ottoman territory either.
While Greece might, and most probably would, still have achieved independence, it would not have come so early without European intervention.
"Into the face of the young man who sat on the terrace of the Hotel Magnifique at Cannes there had crept a look of furtive shame, the shifty, hangdog look which announces that an Englishman is about to talk French." - P.G. Wodehouse, The Luck of the Bodkins