Rule 3.03

Rule 3.03

A player, or players, may be substituted during a game at any time the ball is dead. A substitute player shall bat in the replaced player’s position in the team’s batting order. A player once removed from a game shall not re-enter that game. If a player who has been substituted for attempts to re-enter, or re-enters, the game in any capacity, the umpire-in chief shall direct the player’s manager to remove such player from the game immediately upon noticing the player’s presence or upon being informed of the player’s improper presence by another umpire or by either manager. If such direction to remove the substituted-for player occurs before play commences with the substituted-for player improperly in the game, then the substitute player may enter the game. If such direction to remove the substituted-for player occurs after play has commenced with the substituted-for player in the game, then the substitute player shall be deemed to have been removed from the game (in addition to the removal of the substituted-for player) and shall not enter the game. If a substitute enters the game in place of a player-manager, the manager may thereafter go to the coaching lines at his discretion. When two or more substitute players of the defensive team enter the game at the same time, the manager shall, immediately before they take their positions as fielders, designate to the umpire-in-chief such players’ positions in the team’s batting order and the umpire-in-chief shall so notify the official scorer. If this information is not immediately given to the umpire-in-chief, he shall have authority to designate the substitutes’ places in the batting order.

Rule 3.03 Comment: A pitcher may change to another position only once during the same inning; e.g. the pitcher will not be allowed to assume a position other than a pitcher more than once in the same inning.

Any player other than a pitcher substituted for an injured player shall be allowed five warm-up throws. (See Rule 8.03 for pitchers.)

Any play that occurs while a player appears in a game after having been substituted for shall count. If, in an umpire’s judgment, the player re-entered the game knowing that he had been removed, the umpire may eject the manager.


DISCUSSION
"A manager may give the umpire a double-switch while defensive players are entering the playing field. However, in the unlikely event that an unannounced pitcher takes a position on the pitching rubber before the manager confers with the umpire, Official Baseball Rule 3.08(a)(1) provides such pitcher to have entered the game. In such case, a subsequent attempt by the manager to make a double-switch shall not be allowed." [MLBUM]

During the eighth inning of a game against the New York Mets in 2008, San Diego Padres Manager Bud Black pinch hit Edgar Gonzalez for reliever Cla Meredith in the ninth position in the lineup, and Brian Giles pinch hit for second baseman Tadahito Iguchi in the second position.  During the middle of the inning Black motioned to plate umpire Tim Tichenor with two fingers and a chopping motion.  Tichenor interpreted this motion as an indication that Black wanted his new reliever, Bryan Corey, to replace Gonzales and annotated the lineup card.  Black intended that Gonzales would remain in the game at second base and pitcher Corey would bat in the second position.  After Corey took the mound and began his warm-up tosses, Tichenor and Black discussed the situation. 

In this case, Black should have notified Tichenor of his new pitcher and his place in the lineup.  Arguably, Black could have remedied any confusion before Corey took the mound.  Ambiguous gesturing to the umpire led to the confusion.  See story at: http://mlb.mlb.com/news/article.jsp?ymd=20080807&content_id=3269604&vkey=news_sd&fext=.jsp&c_id=sd

Unannounced double switch: http://mlb.mlb.com/video/play.jsp?content_id=5183641

Leads to protest, read story: http://mlb.mlb.com/news/article.jsp?ymd=20090621&content_id=5459358&vkey=news_nyy&fext=.jsp&c_id=nyy

Pitcher moved to another position, then returns to pitch in same inning [Rule 3.03 CMT]

http://mlb.mlb.com/news/article.jsp?ymd=20090712&content_id=5854550&vkey=news_chc&fext=.jsp&c_id=chc

Another example of pitcher moved to another position.

http://mlb.mlb.com/video/play.jsp?content_id=18384337

The only penalty for illegal reentry is removal of the offender from the game. All action in which the illegal substitute took part is legal. If caught before a play or pitch, replace the player. If caught after a play or pitch, eject the player, but keep the play. The manager may also be ejected, if  warranted.