You would be hard pressed to find a player in the MLB who would not do whatever it takes to win, regardless of his personal feelings about his teammates. The only situation I can think of where a player's personality might negatively affect the team, is if the personality of the player is toxic to the point of being extreme. For example, a complete nutcase who goes out of his way to make life miserable for his teammates. Other than that, ******* or not, players want to win and they will put their personal feelings aside in order to do so.