The Infield
First base.
First base is the first of four bases that must be touched (while running) by a player on the batting team in order to score a run. In contrast to second and third base, it is permitted for a runner to overrun first base without being in jeopardy of being put out after contact is made with the base, provided the runner makes no move to attempt to advance another base. A batter who accumulates four balls or is hit by a pitch is automatically permitted to advance to first base.
The first baseman is the defensive player responsible for the area near first base. Professional first basemen are often tall both to present a large target to which other fielders can throw and because their long limbs give them a larger range to reach errant balls. Additionally, players who are left–handed are preferable for first base as their glove will be closer to the third baseman and shortstop, which makes for a shorter throw and hastens the arrival of the ball in a close play where the fielder must throw the ball all the way across the diamond. In the numbering system used to record defensive plays, the first baseman is assigned the number 3.
Second base
Second base, or 2B, is the second of four stations on a baseball diamond which must be touched in succession by a base runner in order to score a run for that player's team. Second base is typically defended by the second baseman and the shortstop. Second base is also known as the keystone sack. A runner on second base is said to be in “scoring position,” owing to the high likelihood of reaching home plate and scoring a run from second base on most base hits. Since second is the farthest base from home plate, it is the most common target of base stealing.
The second baseman and shortstop ideally possess quick hands and feet and the ability to release the ball rapidly and with accuracy. One will usually cover second base when the other attempts to field the ball. Both players must communicate well to be able to make a double play. Particular agility is required of the second baseman in double play situations, which usually forces the player to throw towards first while his momentum carries him in the opposite direction. In the numbering system used to record defensive plays, the second baseman is assigned the number 4, and the shortstop 6.
Third base
Third base is the third of four bases a baserunner must touch in a counterclockwise succession in order to score a run. Many batted balls that result in the batter being put out (such as a sacrifice fly) may nevertheless allow a runner to reach home plate and score a run from third base, provided that the third and final out is not recorded before he can do so. A runner on third base is therefore particularly valuable to the batting team when fewer than 2 outs have been recorded.
The third baseman, abbreviated 3B, is the defensive player whose responsibility is to defend the area nearest to third base. A third baseman ideally possesses quick reaction to batted balls and a strong arm to make the long throw to first base. In the numbering system used to record defensive plays, the third baseman is assigned the number 5.
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