Kapaernick did not make the sales "surge", it was Labor day sales prices.
Nike stock was kicking ass before Kapernick ads ran. If Nike had Maria Sharapova do ads it would be at the same place.
On a side note, I was talking to sportswear shop sales person in Hong Kong, They said Nike sales have stopped and Adidas sales took off because of the Serena Williams US Open temper tantrum and loss to Naomi Osaka. Serena Williams disgraced the game and America.
Winners wear Adidas