The Yankees do not have an official code of conduct for their players. But, like most teams, there in a built-in code that surrounds what is commonly called “Yankees Tradition” that speaks volumes as to what is expected.
Recently, for example, Clint Frazier reined himself in to be in conformance with the “no hair below the shoulders” request. And at one point in his career, Don Mattingly challenged the hair policy and was benched along with four other Yankees.
But generally, the Yankees treat their players in their farm system differently, almost like the players there are attending kindergarten where they learn to live by certain rules.