Everybody calm down.
They're not Adidas hats, they're just hats sent by a bat company. Wearing them in the fall because the hats for the season are not here yet and Serrano didn't want a hodgepodge of extra hats from last year being worn by the team this fall. Obviously, they're not the right color. They're mesh. They're just for fall practice.
Contractually, we have to wear Adidas hats for games in the spring, and those have always been the proper color.
The overreaction to something worn in an off-season practice is pretty amazing.