From BR Bullpen
Instant replay was introduced by Major League Baseball on August 28, 2008. MLB became the last of the four major North American sports leagues to use instant replay, mostly over the objections of baseball purists and commissioner Bud Selig, who believed that replays would break the longstanding tradition of putting each game's fate in the hands of the umpires on the field. Others objected to replays lengthening an already long game.
Under its initial form, the instant replay only applied to home run calls in three situations:
- to determine whether the ball is fair or foul;
- to determine if the ball has left the playing field;
- to determine if the home run was subject to fan interference.
The decision to ask for instant replay to be used was made by the umpire crew chief, who could also decide if a call should be reversed.
Every Major League ballpark was installed with a television monitor and a secure telephone link to MLB headquarters in New York, where every game being played is monitored by an expert technician and an active umpire (initially, reviews were done either by an umpire supervisor or a former umpire). Should the crew chief at the ballpark decide to ask for the instant replay to be used, he calls the technician in New York who transmits the appropriate footage to the crew chief and umpire crew (the umpire supervisor or former umpire at MLB headquarters is not in direct communication with any of the umpires at the ballpark).
The crew chief must have clear and convincing evidence that the call made by the umpire on the field was incorrect, and the decision to reverse the call rests solely with the crew chief. Once the instant replay has been used, the decision is final; neither team is allowed to argue the decision taken by the crew chief to either reverse the call made on field, or to let it stand.
Should a home run call be reversed, the crew chief then decides on the placement of the baserunners.
Further to their advertising deal with MLB during the 2008 season, all monitors used for the instant replay are SHARP Aquos models. []
 First use of the instant replay
The first MLB instant replay was used after a hit by Yankee Alex Rodriguez during a game on September 3, 2008 at Tropicana Field. The hit was initially ruled to be a home run by third base umpire Brian Runge, but the manager and catcher from the Tampa Bay Rays argued that the ball was foul and asked for a review. After a discussion among the umpires, the crew chief allowed the replay to take place, and the home run call was upheld.
 First reversed home run call
The first 13 reviews all showed correct home run calls. On May 13, 2009, the first homer was overturned. Lance Barksdale ruled a Adam LaRoche hit a home run but on replay, it was found to be a double. LaRoche said he agreed with the ruling.
 First use in the World Series
In Game 3 of the 2009 World Series, on October 31, 2009, Alex Rodriguez hit a high fly ball to the right field corner of Citizens Bank Park in Philadelphia which appeared to hit the top of the fence. Umpire Jeff Nelson originally ruled a double, but New York Yankees manager Joe Girardi came out to argue the call and urge the umpires to review the video evidence. When they did so, it became clear that the ball had in fact hit the lens of a television camera in the first row of the stands; Rodriguez was granted a two-run home run.
 Expansion of Instant replay
With the renewal of the Collective Bargaining Agreement after the 2011 season, Major League Baseball sought to extend the use of instant replay to additional situations, namely:
- whether a ball hit down the foul line is fair or foul;
- whether a fly ball was caught or trapped; and
- whether fan interference occurred anywhere on the field.
This came as a result of several controversial calls since the introduction of instant replay on home run calls, particularly in the 2009 Postseason. However, MLB was unable to reach an agreement with the Players' Union and the World Umpires Association prior to the start of the 2012 season, and adoption of these additional uses was postponed until 2013. Among the issues at play were the uneven number of camera angles available in different ballparks and disagreements on how to implement the additional possibilities for review in a way that was least disruptive to the flow of the game. On July 27, 2012, Commissioner Selig confirmed that there was agreement for expansion of instant replay in the first two of these areas in 2013.
On August 15, 2013, Selig announced plans to expand review even further, by allowing each manager up to three challenges per game. After receiving agreement from the Players Association and the World Umpires Association, the new rule was formally accepted at an owners meeting on January 16, 2014, in time for it to be implemented at the start of the 2014 season. Under these rules, each manager starts a game with one challenge; if he is successful, he can challenge one other decision. From the 7th inning onward, the umpire crew can also decide on its own to submit a decision to video review. Almost all decisions can now be reviewed (e.g. whether batted balls are foul or fair, tag and force plays, balls caught or trapped, etc), but not decisions regarding balls and strikes, and obstruction or interference calls.
The expansion of instant replay meant that six additional umpires were added to the major league staff before the 2014 season, in order to be able to make judgments on disputed call from MLB's Advanced Media headquarters in New York. Former major league umpire Justin Klemm was hired to oversee the implementation of the new system. Because of the requirement for extra cameras and other additional technical equipment to be set up in ballparks, the new replay rules were not in effect for the first two games of the season, played in Sydney, Australia. Thus the first instances of instant replay all took place on March 31st, when a majority of teams opened their season (the only game played the previous day had not necessitated recourse to the new rules). The first manager to request a review was Rich Renteria of the Chicago Cubs, who asked that an out call on Jeff Samardzija at first base be reviewed, but the replay confirmed the umpire's call. Shortly after that, Fredi Gonzalez of the Atlanta Braves became the first manager to have a call successfully overturned, when a video review confirmed that Milwaukee Brewers runner Ryan Braun was out at first base, and not safe as umpire Greg Gibson had originally ruled. Finally, umpire Mike Winters became the first umpire to initiate a review himself, asking to look at whether Oakland A's catcher John Jaso had legally blocked the plate in tagging out Michael Brantley of the Cleveland Indians, something which the review confirmed.
With the return on the first year of using expanded instant replay largely positive, MLB announced in June of 2015 that it would open a second review center, in San Francisco, CA, to provide umpires some more decent working hours, especially during night games played on the West Coast, but also to provide some redundancy in case there ever was a technical problem with one of the centers. One dissenting voice about the rule's success was Chicago Cubs manager Joe Maddon, who stated after a couple of review requests did not go his way that the centers should be staffed not by umpires, but by "a bunch of nerds" more familiar with the technology used to make the decisions.
 Further Reading
- Gil Imber: "Reviewing Instant Replay: Observations and Implications from Replay's Inaugural Season", The Baseball Research Journal, SABR, Vol. 44, Number 1 (Spring 2015), pp. 45-53.
- Paul White: "Upon further review, instant replay a mixed bag", USA Today Sports, April 10, 2014.