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 players team. A first baseman is the player on the team playing defense who fields the area nearest first base, in the numbering system used to record defensive plays, the first baseman is assigned the number 3. Also called first sacker or cornerman, the first baseman is ideally a tall player who throws left-handed and possesses good flexibility, 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 they often are power hitters who have a substantial number of home runs and extra base hits while maintaining a.270 plus batting average. 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 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 baseman, shortstop. As a result, first base is not usually perceived to be as physically demanding as other positions, however, it can also be a very hard position to play, a large amount of concentration and timing is required. Though many play at first base their entire career, it is common for 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 reduction in playing time. Catchers and corner outfielders are often moved to first base due to deteriorating health or if their fielding abilities at their position are detrimental to the team. When first base is not occupied by a baserunner, the first baseman usually stands behind first base, the distance he plays from the base and foul line is dependent on the current hitter and any runners on base. The exact position may depend on the first basemans experience, preference. For a known right-handed pull hitter, the first baseman might position himself further towards the second basemans 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 a ball hit down the line. To protect against a bunt on the first base side of the infield, 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
Sean Casey, former first baseman for the Cincinnati Reds tries unsuccessfully to keep his foot on the base while receiving a throw from an infielder.
A high school first baseman takes a throw from the third baseman in an attempt to have the runner called "out".