In the picture, look at the zoomed-in region. There were ~4 million total votes. The up/down spikes are about 3% in each direction (y-axis), and they occurred after more than 75% (x-axis) of the votes had been received (~3 million votes). In order to cause a single-direction 3% shift (x-axis), you’d need more than 100,000 votes. But 100,000 is more than 2% of the total votes cast (y-axis). So an instant up/down shift is impossible (it can’t be instant; you have to move 2% along the x-axis before going back the other way).

Compensating for overkill?