Now, consider this:
So the data wasw collected from the Tropical Paradise server. TP is hosted in Europe. That means that non-europeans were by far the largest group of high-pingers (the amount of people with a really shitty connection excluded, they're an insignificant group).
Now, those non-euro's will, for the large majority, be Americans.
You haven't then ruled out another explanation to the performance difference. It might be that the Americans are just not very good at the game? One would have to compare the K/D of TP with a comparable All-american server and see if the K/D's differ.