The three outfielders are positioned so as to best be able to catch or field balls that are batted over or through the infield. The three outfield positions are left fielder, centre fielder, and right fielder. Outfielders must be able to judge the trajectory of flies and have enough speed to run to the point where the ball will come down. Batted or thrown balls that pass beyond the infielders along the ground must be run down and picked up by the outfielders. Outfielders adjust their positions in response to each batter’s hitting tendencies. Strong throwing arms are essential, as is accuracy in throwing the ball to the right point in the infield. Right fielders typically have the strongest and most accurate throwing arms among outfielders. The centre fielder is chosen for his speed and expert judgment of fly balls. The centre fielder not only stations himself at a strategic point for each batter but often directs the playing positions of his outfield teammates. Almost invariably the most skillful defensive outfielders in baseball history, such as Tris Speaker, Joe DiMaggio, Willie Mays, and Ken Griffey, Jr., have been centre fielders.

Infielders

The infielders form the inner ring of defense. They sometimes catch line drives on the fly, but mainly they pick up ground balls that roll toward the outfield or shoot swiftly across the grass on one or more bounces. When a batted ball strikes the ground, the play becomes a race between the batter running to first and an infielder trying to gain control of the ball and throw it. Like the outfielders, the four infielders shift position to guard against each batter’s individual strengths. They have the additional responsibility of guarding the bases when occupied. When a ball is batted along the ground, only one infielder is called upon to gain control of it, but at least one other almost always covers a base to take the throw. Depending on the situation, sometimes two bases must be covered for a possible throw, sometimes all four. On a ball hit into the outfield, an infielder may need to position himself to receive a throw from an outfielder.

Each position has its special fielding requirements. Usually positioned to the left of second base, shortstop is the most difficult and demanding of the defensive positions, requiring outstanding agility, range, and a strong throwing arm. The throw from the shortstop to first base is the infield’s longest and most difficult. The second baseman, who is typically positioned to the right of second base, does not require an exceptionally strong arm, but he does need as much range and agility as the shortstop. Together the shortstop and second baseman form the keystone of the defense, as both cover second base, take most of the throws from the outfield, and handle the majority of ground balls. Many of the game’s greatest fielding players have been shortstops and second basemen, among them Honus Wagner, Pee Wee Reese, Dave Concepción, Ozzie Smith, and Omar Vizquel at shortstop and Nap Lajoie, Charlie Gehringer, Bill Mazeroski, Joe Morgan, and Roberto Alomar at second base.

The third baseman, playing to the right of third base and nearer the batter than the shortstop or second baseman, is not called on to cover as much ground, but his reflexes must be exceptional. The long throw across the infield requires a strong and accurate arm. First basemen are typically physically large in order to provide a big target for throws to first base. The first baseman’s fielding of grounders is made easier by his position near the base toward which the batter is running. First basemen are often left-handed, an advantage in throwing from their position, and are generally among the most powerful hitters in the lineup.

The battery

The pitcher and catcher together are known as the battery or as batterymen. As a fielder, the pitcher may function as an emergency first baseman, and he fields bunts or other infield grounders hit his way. The ability of the pitcher to quickly transition from his pitching motion to a fielding stance can greatly improve his team’s overall defense.

The “good hands” essential to every player are especially important for the catcher. Throughout the game he must catch the pitched balls not hit by the batter and sometimes catch pitches that strike the ground near the plate. The catcher also needs good agility behind the plate. He may need to move his body quickly to knock down an off-target pitch, chase a catchable foul ball, or pounce on a bunt. The catcher’s throwing arm is a valuable element in his team’s defense. Base runners are cautious of straying too far from their bases when the catcher has a quick and strong arm. Not surprisingly, a strong throwing arm has been the hallmark of baseball’s greatest catchers, including Mickey Cochrane, Bill Dickey, Yogi Berra, Johnny Bench, and Iván Rodriguez.

Important as is his fielding, the catcher functions even more crucially as the counselor of the pitcher, as well as of the rest of the team. As the only player in the defensive lineup who has the whole game in front of him at all times, the catcher is best placed to advise teammates when necessary.

The putout

Most putouts are made by (1) striking out the batter, (2) catching a ball on the fly, (3) throwing the batter out, or (4) tagging out a base runner.

The batter is allowed two strikes; a third strike results in an out, commonly called a strikeout. A strike occurs when a batter swings at a pitch and misses, when the batter does not swing at a pitched ball that passes through the strike zone, or when the ball is hit foul. A ball hit foul can count as only the first or second strike with one exception—a ball bunted foul can be called strike three. Umpires signal strikes and putouts with an emphatic movement of the right arm. The strike zone is a prescribed area in front of the batter and over home plate. Its upper limit is in line with the midpoint between the top of the shoulders and the top of the uniform pants, and the lower limit is in line with the bottom of the knees. The strike zone is thus an imaginary rectangular box 17 inches (43.2 cm) wide, with the length of its vertical sides dependent on the height of the batter. The perception of where the strike zone begins and ends may vary from umpire to umpire, leading to frustrated fans and irate batters, pitchers, catchers, and managers. Anyone who disputes an umpire’s call of a ball or strike may be thrown out of the game.

A batter is put out if a fielder catches a batted ball before it touches the ground, whether it is a fair ball or foul. A foul tip, a pitched ball that the batter merely flicks slightly with his bat, however, counts only as a strike even if it is caught and held by the catcher, and it does not count as a putout unless it occurs on the third strike.

A member of the batting team is thrown, or forced, out if he bats a ball that touches the ground before being caught (usually by an infielder or the pitcher) and that is then thrown for the putout to the first baseman, who touches first base before the batter reaches the base.

A member of the offensive team is tagged out if, when running the bases and not in contact with a base, he is touched by the ball held by a member of the fielding team.

The force play

Only one runner may occupy a base at any given moment. It is therefore possible for a runner to be thrown out at second base, third base, or even home plate without being tagged. The batter is entitled to try to reach first base safely the instant he hits a fair ball that strikes the ground. If a teammate is on first when the ball is hit, that base runner is no longer entitled to first base and must run to second. If runners are on first and second or on all three bases, they are all forced to run when the batter hits a fair ball that strikes the ground. Any base runner forced to run can be put out, or retired, by a fielder having the ball who can touch the next base before the runner reaches it.

This method of retiring base runners is called the force play. With first base occupied and the ball driven along the ground to the pitcher or an infielder, the ball often can be thrown first to second base for a force out of the man from first base, then relayed to the first baseman to retire the batter—two outs on one play, a double play. Although double plays can be initiated by force outs at home or third base, the second-to-first double play is the most common form.

A runner also can be thrown out without being tagged if he has left his base before a fly ball is caught. With the catching of the fly, the runner must return to the base he just left (known as tagging up) before being eligible to advance. If the player catching the fly throws the ball to that base before the runner returns and tags up, the runner is retired. On the other hand, after the catch the runner may attempt to reach the next base, where a tag is required to put him out.

The infield fly rule protects base runners from the deception of an infielder who may allow an infield fly ball to drop, thus setting up an easy force play. The rule applies only if both first and second are occupied by runners and there are fewer than two out. The batter is automatically out when the rule is invoked.