He revealed that his hair “gets super bristly” if he doesn’t properly wet it before hitting the field. his teammates don’t seem to mind whatsoever. Garrett Stubbs, another player for the Phillies, said, “It’s called having some f–king edge. That guy knows how to find his f–king edge.”
According to Sporting News, the greasy appearance of Brandon‘s hair is directly related to the heavy amount of water he dumps on his head in order to create the right effect.
Source: https://www.distractify.com/p/brandon-marsh-hair