Editing Baseball rules (section)

===Substitutions===
{{Tone|section|date=April 2015}}
[[File:Ivan Nova (6128539633).jpg|thumb|Pitchers are generally substituted during [[Mound visit|mound visits]] (team gatherings at the pitcher's mound).]]
Each team is allowed to substitute for any player at any time the ball is dead. A batter who replaces another batter is referred to as a ''[[pinch hitter (baseball)|pinch hitter]]''; similarly, a ''[[pinch runner (baseball)|pinch runner]]'' may be used as a replacement for a baserunner. Any player who replaces another player between innings, or while the team is in the field, is known as a "defensive replacement". A replacement pitcher is called a [[relief pitcher]].

Any replacement is a permanent substitution; the replaced player may not return to the game under any circumstances. Thus, a pitcher that has been removed from the game and replaced by a relief pitcher cannot return to pitch later in the game, and any batter who is replaced by a pinch-hitter cannot take the field in the following inning (or even bat again if his turn comes up again in the same inning). Note however, that two players can switch defensive positions at any time, and both can still stay in the game—because neither has actually been <u>removed</u> from the game.  

In a notable example from 1952, the starting pitcher, [[Harvey Haddix]], switched positions with outfielder [[Stan Musial]] in the middle of the game, who became a relief pitcher. Later in the game, after Musial had faced one batter, the players switched back, with Haddix relieving the outfielder-turned relief pitcher. This meant that in practical terms, the starting pitcher was relieved by another pitcher, but then came back to relieve the relief pitcher.<ref>{{Cite web |url=https://www.baseball-reference.com/boxes/SLN/SLN195209280.shtml |title=Chicago Cubs at St. Louis Cardinals Box Score, September 28, 1952 |access-date=2018-03-27 |archive-url=https://web.archive.org/web/20170924184319/https://www.baseball-reference.com/boxes/SLN/SLN195209280.shtml |archive-date=2017-09-24 |url-status=live }}</ref> Note that this did not violate baseball's permanent substitution rule in any way, as at no time did either player leave the game.

This "permanent substitution" rule is in contrast to some other sports, such as basketball, hockey and American football, that practice "free substitution". In some cases, if the defensive manager responds to the entrance of a pinch-hitter by bringing in a new pitcher, the pinch-hitter may be replaced by another pinch-hitter without having come to the plate, in which case the first pinch-hitter is considered to have entered the game and is ineligible to do so later.  However, the defensive manager may not replace a pitcher who has not pitched to at least one batter (three batters in MLB as of 2020), except in case of injury. The reentry of a replaced player into the game is a violation of the permanent substitution rule; if the defense has more than nine players on the field at any time, the umpire must determine who is the tenth player, and that player is ejected from the game.

Many [[amateur]] leagues allow a starting player who was removed to return to the game in the same position in the batting order under a re-entry rule. Youth leagues often allow free and open substitution to encourage player participation.

====Pitchers as batters, and the designated hitter====
Pitching is a specialized skill, particularly in the collegiate and professional ranks; so most pitchers are relatively poor hitters, or, those who were skilled batsmen are simply unable to adequately hone their hitting skills to be comparable to regular position players. As a result, unless keeping a given pitcher in the game is a higher priority than the prospect of immediate offense, it is common to substitute for a pitcher when he is due to bat. This pinch hitter is often then replaced by a relief pitcher when the team returns to the field on defense.

A more complicated tactic is the [[Double switch (baseball)|double switch]], in which a pitching change is accompanied by the simultaneous replacement of another fielder. If the pitcher is due to bat soon, and the outgoing fielder batted recently, the new pitcher will take the outgoing fielder's place in the batting order, thus delaying his next time at bat. A common variation on this involves the introduction of a player who has just pinch hit (or pinch run for the pinch hitter) into the defensive alignment; unless this player becomes his team's next pitcher, another field player departs the game, and the new pitcher then assumes that player's place in the batting order.

Many leagues allow [[designated hitter]]s, notably [[Major League Baseball]]'s [[American League]] (which instituted the Designated Hitter in 1973 to boost offensive output). A designated hitter (or DH) is a player whose sole purpose is to hit when it would normally be the pitcher's turn (or, in some leagues, if the pitcher is a good batter, another weaker batter). This is not considered a substitution, but rather a position, albeit a purely offensive one. A designated hitter does not play in the field on defense and may remain in the game regardless of changes in pitchers. If the designated hitter is moved to a fielding position, the team loses the DH, and the fielder whose position was taken by the former DH is replaced by the pitcher, who assumes that player's position in the hitting lineup.

The use of the designated hitter, which reduces the need for complicated strategy like the double-switch, is opposed by many baseball traditionalists. Nevertheless, it is used today at most levels of baseball in the United States and abroad. [[Major League Baseball]]'s [[National League (baseball)|National League]] was the most prominent league that required pitchers to bat, until allowing the designated hitter beginning with the 2022 season.<ref>{{cite web |url=https://www.mlb.com/glossary/rules/designated-hitter-rule |title=Designated Hitter Rule |website=mlb.com |publisher=Major League Baseball |access-date=September 20, 2022}}</ref>