First base, or 1B, is the first of four stations on a baseball diamond which must be touched in succession by a baserunner in order to score a run for that player's team. A first baseman is the player on the team playing defense who fields the area nearest first base, and is responsible for the majority of plays made at that base. In the numbering system used to record defensive plays, the first baseman is assigned the number 3.
Also called 1b, first base, first sacker or cornerman, the first baseman is ideally a tall player with good flexibility and quick reflexes. Flexibility is needed because the first baseman receives throws from the other infielders, the catcher and the pitcher after they have fielded ground balls. In order for the runner to be called out, the first baseman must be able to stretch towards the throw and catch it before the runner reaches first base. First base is often referred to as "the other hot corner"—the "hot corner" being third base—and therefore, like the third baseman, he must have quick reflexes to field the hardest hit balls down the foul line, mainly by left-handed pull hitters and good right-handed hitters that possess the ability to hit to the opposite field.
Good defensive first basemen, according to Bill James, are capable of playing off first base so that they can field ground balls hit to the fair side of first base. The first baseman then relies upon the pitcher to cover first base to receive the ball to complete the out. Indications of a good defensive first baseman include a large number of assists and a low number of throwing errors by other infielders.
The nature of play at first base often requires first basemen to stay close to the bag to hold runners or to reach the bag before the batter. First basemen are not typically expected to have the range required of a third baseman, shortstop, second baseman or an outfielder. As a result, first base is not usually perceived to be as physically demanding as other positions. However, it can be also a very hard position to play; it takes a lot of concentration. Though many play at first base their entire career, it is common for veteran players to be moved to first base in order to extend their careers or to accommodate other recently acquired players. Facing a possible trade or a considerable reduction in playing time, a player will usually opt to move to first base instead. Catchers and corner outfielders are often moved to first base due to deteriorating health or if their fielding abilities at their original position are detrimental to the team.
When first base is not being occupied by a base runner, the first baseman usually stands behind first-base and off the foul line. The distance he plays from the base and foul line is dependent on the current hitter and any runners on-base. The normal position is behind first base and off of the foul line, distances from first base and the foul line will depend on the first baseman's experience, preference, fielding ability and the current hitter. For a known right-handed pull hitter, the first baseman will be position himself further towards the second baseman's normal fielding position. For a known left-handed pull hitter, the first baseman will position himself closer to the foul line in order to stop balls hit down the line.
To protect against a bunt on the first base side of the infield, the first basemen will position himself in front of the base and move towards the hitter as the pitch is thrown. As soon as the pitcher commits to throwing towards home plate, the first basemen will charge towards the hitter to field the bunt. During these plays, it is the responsibility of the second basemen to cover first base.
With a base runner present at first base, the first baseman stands with his right foot touching the base to prepare for a pickoff attempt. Once the pitcher commits to throwing towards home plate, the first baseman comes off the bag in front of the runner and gets in a fielding position. If the bases are loaded, or if the runner on first base is not a base stealing threat, the first baseman will position himself behind the runner and appropriate for the current batter.
When waiting for a throw from another player, the first baseman stands with his off-glove foot touching the base, then stretches toward the throw. This stretch decreases the amount of time it takes the throw to get to first and encourages the umpire to call close plays in favor of the fielding team. Veteran first basemen are known to pull off the bag early on close plays to convince the umpire that the ball reached his glove before the runner reached first base. The first baseman also has the responsibility of cutting off throws from the any of the three outfield positions on their way to home plate. Though highly situational, the first baseman usually only receives throws from the center or right fielder.
The first baseman is usually at the end of a double play, though he can be at the beginning and end of a double play. Unusual double plays involving the first baseman include the 3-6-3, 3-4-3, 3-2-3, or a 3-6-1 double play. In a 3-6-3 or 3-4-3 double play, the first baseman fields the ball, throws to second, where the shortstop or second baseman catches the ball to make the first out and then throws back to the first baseman who reaches first base in time to tag first base before the batter reaches first base. For a 3-2-3 double play, the bases must be loaded for the force-out at home plate or the catcher must tag the runner coming from third base out. With a force-out at home plate, the first baseman fields the ball, throws to the catcher, the catcher steps on home plate for the first out, then he throws it back to the first baseman to complete the double play. The 3-2-3 double play with a tag out at home plate is usually not attempted because of the possibility of the catcher not being able to tag the runner and/or block the plate. If the runner at third base is known as a good or fast baserunner, the first basemen will make considerable effort to make sure the third base runner does not advance to home plate for a run by "looking" him back to third base. The primary goal of the first baseman in this instance is to ensure the runner doesn't advance and that the team records at least one out, especially in a close game