Baseball coaches are looking for players who care, and they look for cues about this in a variety of places and ways. Does the player care enough to routinely spend extra time developing his game? Does he care enough to treat the game and those associated with it with respect? Does he care enough about achieving his goals that he keeps his grades up? Does he care enough about wanting to be an integral part of the coaches' team to act and, yes, dress civilly when given the opportunity to be with them?
Part of learning to be a successful adult is discovering that people's expectations vary depending upon the significance of what one is doing. The people whose impressions count most in the case of a baseball visit will tend to expect that a player show that he ranks his presence there above simply hanging out with the guys.