In baseball, a number of coaches assist in the smooth functioning of a team. They are assistants to the manager, or head coach, who determines the lineup and decides how to substitute players during the game. Beyond the manager, more than a half dozen coaches may assist the manager in running the team. Baseball is unique in that the manager and coaches typically all wear numbered uniforms similar to those of the players. One notable exception to this was Baseball Hall of Fame manager Connie Mack, who always wore a black suit and never dressed like a player while managing.
The team is assisted by two on-field coaches when it is at bat. They are stationed near first and third base to signal and direct the runners and batters. These coaches are called the first base coach and third base coach, respectively, and position themselves in designated coach's boxes. The third base coach typically has more responsibility because he must quickly and accurately signal to a baserunner whether he should attempt to score on a batted ball. Often these two coaches have other responsibilities outside of in-game situations; it is not uncommon for one of these coaches to serve as the team's fielding instructor and the other as baserunning instructor.
In addition, a team may have several other coaches who specialize in certain disciplines. A pitching coach mentors and trains pitchers. A hitting coach works with players to improve their hitting techniques and form. A bullpen coach is similar to a pitching coach but works primarily with relief pitchers in the bullpen. Another coaching position is the catching instructor who advises catchers. Many teams also employ special instructors in defense and baserunning. The position of bench coach is relatively new in baseball. The bench coach's responsibilities include helping to set up the day's practice and stretching routines before a game. Once the game begins, the bench coach acts mostly like an assistant manager, offering the manager situational advice. The bench coach also takes over the duties of the manager if the manager is ejected from the game. Because of MLB rules on the number of coaches, the same person may hold more than one of these positions.
Teams may hire more than one person for any given coaching position based on the team's needs. Teams may also hire people to serve as general coaches or instructors without any specific title who instead may perform any one or more of the duties listed above. Often coaches will be former players themselves who can teach current players from their own experience.