A coach is a person who assists the Manager in running a baseball team. In modern baseball, coaches tend to have specialized duties:
- the first base coach stands in a chalk-line box in foul territory between first base and the right dugout; his main duty is to relay signs to the batter and to tell runners whether to stop at first base or continue further;
- the third base coach also stands in a box in foul territory, but between third base and the left dugout; he also relays signs to the batter and is responsible for directing traffic at third base; third base coaches tend to receive an inordinate amount of blame when runners are thrown out at home plate;
- the bench coach is an assistant to the manager, and is usually responsible for various aspects of in-game strategy. Bench coaches thus are frequent candidates to fill managerial vacancies;
- the pitching coach is responsible for instruction for the pitchers; he will usually visit the mound when a pitcher is tiring or when there is a need to relay instructions to him in mid-inning, although it is usually the manager himself who comes out when there is a pitching change;
- the hitting coach is responsible for working with the team's hitters, especially on questions of mechanics; in contemporary baseball, he is often helped by an assistant hitting coach;
- the bullpen coach works with the team's relief pitchers, ensures that they are ready to enter the game and supervises their warm-up.
In addition to these positions, a team may have several other coaches who specialize in certain disciplines. One such position is the catching instructor who advises catchers. Many teams also employ special instructors in defense and baserunning. Some teams, the Atlanta Braves, for example, employ on their staff a strength and conditioning coach Often, the base coaches have other responsibilities outside these in-game situations; it is not uncommon for either of these coaches to serve as an outfield instructor or infield instructor, or as a baserunning instructor.
Other duties performed by coaches include supervising batting practice and other exercises, placement of players on defense (often by a coach sitting high in the stands, thus having a full view of the playing field), and specialized skills such as bunting, baserunning or sliding. Often, such specialized coaches are brought in to help with the instruction of fundamentals in spring training, but do not stay with the team for the remainder of the season.
Like managers, coaches usually wear the team's uniform and have a uniform number. From time to time, coaches are added to the active roster to act as pinch hitters or defensive replacements, usually during the time when active rosters are expanded in September.
Coaches, in the form of base coaches, have existed almost as long as the game of baseball. However, it is only in the first decades of the 20th Century that the first full-time coaches appeared. Before that, coaching on the bases was done by the manager and other players.
Major league teams began adding full-time coaches in the early years of the 20th century, and their numbers grew over the following decades. Four coaches (two base coaches, a pitching coach and a hitting coach) was the standard arrangement for many years, but numbers began to grow in the 1970s, prompting Major League Baseball to decree a formal limit. From 1981 to 2012, teams were allowed to have only six coaches in uniform. Many teams had additional coaches who sat in the stands during games. In 2013, teams were allowed a seventh coach, with most choosing to use the opportunity to add a second hitting coach. In the minor leagues, there was usually only one coach per team, with roving batting and pitching coaches moving from team to team within an organization to provide specialized instruction. Since the beginning of the 21st century, most minor league teams have full-time pitching coaches in addition to a hitting coach.
A majority of Major League managers served as coaches before earning their first managerial assignment, and many of them return to coaching after losing the top job. Almost all coaches are former major league or minor league players.
Coaches and their contribution to winning have tended to be overlooked over the years. As a result, it is very difficult to find a complete historical list of major league coaches. This is changing somewhat however, with successful pitching coaches such as Leo Mazzone or Rick Peterson, or successful hitting coaches such as Charley Lau or Walt Hriniak being in high demand and commanding commensurate salaries.
- Thomas Boswell: "How to Control the Arms Race", in Why Time Begins on Opening Day, Penguin Books, New York, NY, pp. 117-127 (an article about the work of the pitching coach).
- Thomas W. Brucato: Baseball Skippers and Their Crews: The History of Every Major League Manager and Coach, 1871-2007, St. Johann Press, Haworth, NJ, 2008. ISBN 978-1-878282-50-7
- Dan Fox and Neal Williams: "The Traffic Directors", in The Baseball Research Journal, number 36 (2007), SABR, Cleveland, OH, pp. 19-26 (an extensive study of third base coaches during the 2000-2006 period, which finds no evidence that directing runners at third base is a measurable skill).
- Gabe Lacques: "‘Adapt or die’: MLB staffs have new look as coaches go from lab to dugout", USA Today, March 7, 2019.