The third baseman is the infielder closest to third base. His position is associated with the number 5. Third base is called the 'hot corner' because of all the hard-hit balls from right-handed hitters that go down the third-base line. As with a first baseman, second baseman, or shortstop, the third basement typically fields ground balls, line drives, and pop flies hit in his general direction.
The third baseman can occasionally make an out at third base by either running with the ground ball hit to him at third base, reaching third base before a runner running from second base reaches third base. In such an instance runners are on first and second base when a fair ball is hit on the ground. Usually if the ground ball is hit to the third baseman he is moving away from third base and has a much easier (or even possible) throw to the shortstop or second baseman covering second base or the first baseman or pitcher covering first base. With the bases loaded, a third baseman might throw to home plate to get an out at home.
The third baseman has a long throw to turn a ground ball hit to him if he must throw to first base, but not so long a throw to second base. Given a choice between getting a baserunner out at second or the batter running to first base, he will go for the out at second base if at all possible.
On a fly ball (usually foul) that a third baseman catches, a baserunner might tag up and advance a base (including scoring from third base). In rare circumstances a third baseman has such a play available.
As with a shortstop, the third baseman can turn a double play under the right circumstances, typically throwing first to the second baseman who then throws to first to get the batter out at first. Such a double play is called "around the horn". Third basemen ordinarily turn far fewer double plays than do second basemen or shortstops because
- such takes two fairly-long throws
- third basemen cannot go far to his right to field ground balls because such balls are foul ground, in contrast to a second baseman or shortstop who can go far to the left or right to field a ground ball.
A strong and accurate throwing arm is essential to a third baseman, as are overall agility and good reflexes.
Very rarely does a third baseman receive a thrown ball from any fielder (including a pitcher or catcher) that allows the third baseman to reach third base before a baserunner obliged to run to third base. More likely the third baseman tries to tag a baserunner who makes an unwise run from second bass to third base.
On bunts and weak ground balls, the third baseman may need to charge the batted ball so that he can make a play at a base other than third base. Third basemen may be involved in rundown plays and in stopping a steal of third base. On fly balls they may position themselves to take a throw from an outfielder and then relay the throw accurately to home plate in an effort to get an out at the home plate (and turn what otherwise would be a run into an out).
On line drives that a third baseman catches, he might be able to throw the ball to a base that the baserunner has vacated (or run to third base) to have the ball at the base before the baserunner can return. In such a case, the baserunner as well as the batter is out.
If speed is less important to a third baseman than to a second baseman or shortstop who has more of a zone in which to field a batted ground ball.
An inadequate third baseman allows many balls hit hard down the third base (foul) line to become doubles and less often triples.
On typical plays involving a third baseman,
- a ball caught in the air (whether a pop fly or a line drive) is "5" if fair, or "5F" if foul.
- a ground ball that the third baseman fields and gets an out tagging a runner obliged to run from second base or reaching third base to tag the bag while holding the ball before the baserunner gets there is a fielder's choice, fc5.
- a play on a ground ball retrieved by the third baseman and thrown to first base for an out is "53".
- a ball grounded to the pitcher that the pitcher throws to third base for an out at third in a fielder's choice play is scored "15fc" From the catcher it is "25fc"; from the shortstop it is "65fc".
- a double play, third baseman to the second baseman to the first baseman ("around the horn") is 543dp.
- an error is e5.