The Lineup Card, Substitutions and the Double Switch
How the batting order is set, why a replaced player cannot return, what a pinch hitter does to the lineup, and how the double switch works, with worked examples and the rules for batting out of turn.
A baseball game is played by nine people on each side, but it is managed through a single piece of paper. The lineup card lists who bats in what order, who plays which position and who starts on the mound. Once the umpire-in-chief accepts it, that order becomes the spine of the game, and every later change has to pass through the rules about substitutions. A manager who understands those rules can squeeze an extra at-bat or an extra inning out of a roster. A manager who misreads them can lose a player for the night.
This article walks through the whole mechanism: how the card is filled out and exchanged, what the batting order is and what happens when someone bats out of turn, how pinch hitters, pinch runners and defensive replacements work, why a player who has been removed cannot come back, how the designated hitter changes the picture, and how the double switch solves a problem that the pitcher's spot in the order used to create. The rules described are the Official Baseball Rules as they stood through the 2025 season; for exact wording and any update, consult the current rulebook on MLB's site.
What goes on the card
Before the game, each manager gives the umpire-in-chief a lineup card, and the managers exchange copies. The card shows nine names in batting order, the defensive position each player will play, and the starting pitcher. In a game with the designated hitter, the DH is one of the nine names, and the pitcher is listed separately from the batting order. Once the card is handed over and the umpire accepts it, it is official. The starting lineup cannot be changed except through the substitution rules, and the batting order on the card is the order in which each side must bat for the whole game.
Positions on the card are written by number in scoring shorthand: 1 for the pitcher, 2 for the catcher, 3 first base, 4 second base, 5 third base, 6 shortstop, 7 left field, 8 center field and 9 right field. If you keep score at the park, the same numbers show up on a scoresheet; the site's scoresheet tool uses them. A double play from shortstop to second to first is written 6-4-3, for example.
The pitcher named on the card has a duty attached to him. The rules require a starting pitcher to face the first batter, or until that batter is retired or reaches base, unless he is injured or ill. The rule keeps the announced starter honest. Fans, fantasy players and bettors all read the card as soon as it is public, a point taken up near the end of this article.
The batting order and what happens if it is wrong
Each player on the offensive team bats in the order in which his name appears on the card, and the order repeats from first to ninth for the whole game. That is the rule that makes the lineup a fixed loop. Everything else is built on top of it.
The first reason managers care about the order is basic. The top of the order comes to bat more often than the bottom, because every game starts with the first hitter and ends wherever the loop happens to stop, so each spot lower in the order gets a little less over a season. Most clubs therefore put hitters who reach base at the top and some of their best power hitters in the middle. How much the exact order matters is a matter of study, and analysts who have looked at it generally find that a sensible order and a slightly better one differ by a small amount compared with the effect of the players themselves.
The second reason is the penalty for getting it wrong. Rule 6.03(b) covers batting out of turn. If a player bats out of order and the defense appeals before the next pitch is thrown to the following batter, the player who should have batted is called out, and the batter after him in the order is the next one up. If nobody appeals, the improper batter is deemed to have batted in the proper turn, and the order simply continues from him. The word "appeal" matters: the umpire does not announce the error, and the defensive team has to notice it and raise it. If the improper batter is caught while he is still at the plate, the proper batter simply steps in and takes over the count. The mistake is rare, but it has happened in professional games.
The phrase to remember is that the lineup is a loop and the loop does not skip. A player removed from the game leaves a slot, and whoever replaces him inherits the slot. That is the whole idea behind substitutions.
Pinch hitters, pinch runners and defensive replacements
A substitution is any change to the card after the game starts. There are three common kinds.
A pinch hitter bats for a player who is due up. He takes the slot of the player he replaces, and the player he replaced is out of the game. If the pinch hitter then stays in to play the field, he plays the defensive position of the man he replaced or some other position, and the manager tells the umpire where.
A pinch runner replaces a runner already on base. Same rule: he takes the slot in the order, and the man he replaced is out of the game. Managers use pinch runners for speed late in close games, trading a slower hitter for a faster runner. The cost is that the hitter's slot is now filled by someone who may be a weaker bat.
A defensive replacement enters to play a position, replacing a player whose glove is weaker than his bat. Managers who lead late often use this swap to protect a lead. Again, the substitute takes the slot of the man he replaces.
The managers must tell the umpire about every change, and the umpire announces it. The umpire announces each change. The burden of reporting a change falls on the manager. The rulebook spells out exactly when a substitute counts as in the game, and Rule 5.10, which governs substitutions, is worth reading once.
Once you leave, you stay out
The rule that gives substitutions their weight is simple: a player who has been replaced cannot return to the game. A starter who leaves, a pinch hitter who is replaced, a runner who is removed for a pinch runner: all of them are done for the night. This is the pro rule. Some amateur rule sets are more flexible. Some allow a starter to leave and re-enter once, in his original batting slot, and many youth leagues have their own substitution and mandatory-play rules designed to give every child a turn. For youth games, the governing body's published rules, such as those at Little League, are the guide, and you should read your league's own rules because they vary by division.
The one-way rule explains much of the strategy. A manager who pinch-hits for a starting outfielder in the seventh must have another outfielder available, or the game will be played with someone out of position. A bench is a finite resource. In a typical major-league game the active roster allows for a limited number of bench players, and every pinch hitter or runner used is a bench player gone. The decision to use one is a decision about how many options are left for the rest of the game, including extra innings.
The same logic applies to pitchers. Since the 2020 season, a pitcher who enters a game must face at least three batters or finish the half-inning, unless he is injured or ill. The three-batter minimum was added to cut down on the situation in which a manager sends in one pitcher to face a single batter. It changed the value of the specialist reliever, and it means that a pitching change is now a bigger commitment than it once was. As of the 2025 season, the rule also limits when position players may pitch: generally in extra innings or when one team leads by a large margin. Players who qualify as two-way players are exempt, and the exact thresholds are in the rulebook.
If you want the equipment side of the rules, the article on the rules for bats, balls and gloves covers it, and counts, walks and strikeouts explains the count logic that pinch hitters step into.
The designated hitter and the Ohtani rule
The designated hitter is a player who bats in place of the pitcher but does not play the field. The American League adopted the designated hitter in 1973. The National League did not use it until the universal designated hitter took effect in 2022, so for almost fifty years the two leagues mostly played by different rules, apart from some interleague and World Series games, and the lineup card in a National League park had the pitcher's name in the batting order. Since 2022 every major-league game uses a DH.
The DH has rules of its own. A DH named on the lineup card must bat at least once unless the opposing team changes pitchers before he comes to the plate. A DH can be replaced by a pinch hitter, who then becomes the DH, and the replaced man is out of the game. A DH who goes onto the field loses that role, and the club gives up the DH for the rest of the game; Rule 5.11 has the details. For that reason, managers are cautious about moving a DH to the field, especially late in games.
In 2022, the same rule change that brought the universal DH added an exception that is called the Ohtani rule, after the player who made it necessary. A starting pitcher can be listed as the DH in the lineup, and if he is removed from pitching he can stay in the game as the DH. Before this, a pitcher listed as DH who left the mound also lost his bat. The rule only matters for players who both pitch and hit at an elite level, and there are very few of them, but it shows how the rules adjust when the game produces something new.
The double switch, step by step
The double switch was invented to solve a problem that no longer comes up as often as it used to: the pitcher's spot in a lineup with no DH. A pitcher who is a weak hitter will bat ninth. When he is replaced with a reliever, the reliever inherits the ninth slot, and if his turn comes up while the game is close, the manager has to choose between letting him bat or pinch-hitting and using up the reliever.
Here is an example, with invented names and no real game behind it. A team's lineup, in order, is a center fielder, a shortstop, a first baseman, a left fielder, a third baseman, a right fielder, a catcher, a second baseman and the pitcher. The team is in the field in the top of the seventh inning, the pitcher is tiring, and the manager wants to bring in a reliever. The bottom of the sixth ended with the fifth hitter, the third baseman, making the last out. That means the batting order picks up with the sixth hitter next inning, then the seventh, the eighth and then the pitcher's spot, ninth. The ninth slot comes up fourth in the next inning, very soon.
A simple one-for-one change would put the reliever in the ninth slot, and he would bat fourth next inning. The manager would either pinch-hit for him right away, wasting him after one batter, or let him hit. Instead, the manager does a double switch. The reliever goes into the fifth slot, the spot of the third baseman who just batted and will not come up for another nine batters. A replacement third baseman, a better hitter than a reliever, goes into the ninth slot, which is the spot of the old pitcher and will come up fourth next inning. Two substitutions are made at once. The old pitcher and the old third baseman are out of the game, the new third baseman bats ninth and the reliever bats fifth.
The result is that a real hitter occupies the pitcher's old slot, and the reliever's first turn is pushed as far away as possible. It also costs something: the old third baseman, who might have been the better fielder, is gone. And the new third baseman has to be on the bench. The double switch is a trade, not a free gain.
The loop explains why it works. The manager picks which slot the reliever will occupy by choosing which fielder to replace. A good rule of thumb is that the replaced position player should be the one who batted most recently, or one who is due last, so that the reliever is as far from the plate as the lineup allows. When the DH is used in every game, the pitcher does not bat, so the double switch loses most of its purpose. Where it still matters is in games played without a DH, which include some amateur and international games, and in games where a club has lost its DH. The typical National League decision of the old kind has mostly disappeared in the majors.
What the rules do not cover
A few situations are not governed by a bright-line rule and are settled by managers' choices. How many pinch hitters to hold in reserve, when to burn the last position player and what to do if the game goes to extra innings with an empty bench: these are strategy. A manager who runs out of position players can put a pitcher in the field, since the rules allow it, or use a position player as a pitcher under the limits above.
The same is true in games decided by rule oddities such as suspended play. The article on rain delays, suspended games and official games explains how a game resumes on another date; the short version is that it picks up with the lineups as they stood, and players who had been removed stay removed.
Umpires also have a part. The crew checks the lineup before the game and keeps track of substitutions, and the way crews are assigned and trained is covered in the article on how umpires are trained and assigned. The unwritten norms around strategy and etiquette are in the unwritten rules of baseball.
Why lineups matter off the field
Lineups are public information that people act on. Fantasy managers set their teams around who is starting, and many fantasy platforms lock a player once his game begins. Bettors read the lineup for the same reason: a star who is out of the lineup changes the expected outcome. Sportsbooks have their own rules about what happens to a bet when the listed starting pitcher changes, and those rules vary, so anyone placing a wager should read the terms of the specific book. Gambling carries risk, is for adults of legal age where it is legal, and help is available at 1-800-GAMBLER. If you want to see how a price translates into a probability, the article on converting baseball betting odds to implied probability explains the arithmetic, and the fantasy baseball pages cover lineup strategy for roster games.
Common questions
Can a replaced player come back into a major-league game? No. Once a player has been replaced, he is out for the rest of the game. Some amateur rule sets allow a starter to re-enter once, and youth leagues have their own rules.
What happens if a team bats out of order? The defense has to appeal before the next pitch to the following batter. If it does, the player who should have batted is called out. If nobody appeals, the improper batter's turn counts and the order continues from him.
What is a double switch? Two substitutions made at the same time, one a pitching change and one a position-player change, so that the new pitcher's turn in the batting order is delayed and a better hitter takes the pitcher's old slot.
Does the designated hitter have to bat? Yes. A DH listed on the lineup card must bat at least once, unless the opposing team changes pitchers before he comes to the plate.
Why did the double switch become rare? It was designed for lineups in which the pitcher batted. Since the universal DH began in 2022, pitchers do not bat in major-league games, so the problem the double switch solved is gone in most cases.
Where to go next
If you are keeping score at a game, the scoresheet tool lets you practice recording substitutions, and the article on how the MLB postseason works shows how managers use the bench when every game matters. For more on the rules, the rules and umpiring topic page collects current reading.