yeah i think prizes should of been based on # of clicks, pattern and size of balloons you clicked, to determine the grade you receive then that grade is used to determine which random prize you get.
i.e. the rarer/harder to get evolutionary items reserved for Grade A, normal evolutionary items for grade C, and stuff like berries for grade E.
If i click 3 fennikens, 3 froakies, 4 pikachus, and those 3 fennekins happened to be all largest baloons, froakies 3 tiniest, pikachu 3 mediums..for example that could be 70 points..
but if next roudn i clicked 3 fennikens that were small, 3 froakies that were large, 5 pikachus that were medium, that could be 15 points.
or say i clicked 3 froakies large, 3 fennikens small, 5 medium pikachus, that would be 40 points even though it's exactly same balloons as first however a different order..
So basically the points are determined on the Size of Balloon, the Pokemon, and Order you in which you click them, plus # of mouse clicks (punished if you clicked wildly as each miss (or click over 10) = a point deduction).