New York, NY (SportsNetwork.com) - Major League Baseball has announced steps to speed up the pace of play and modifications to replay reviews for the 2015 season.

Batters and pitchers will each be affected by the initiatives, which include the enforcement of the batter's box rule and a new time clock to monitor breaks between innings and pitching changes.

"These changes represent a step forward in our efforts to streamline the pace of play," said Major League Baseball commissioner Rob Manfred in a statement Friday. "The most fundamental starting point for improving the pace of the average game involves getting into and out of breaks seamlessly. In addition, the batter's box rule will help speed up a basic action of the game."

The batter's box rule will require batters to keep at least one foot in the box. It applies mostly when there is no one on base.

Exceptions include a swing at a pitch; a pitch that forces the batter out of the box; a wild pitch or passed ball; time granted by the umpire; the pitcher leaving the dirt area of the mound; and the catcher leaving the box to give defensive signals.

A batter can exit the box at those times, but cannot leave the dirt area surrounding home plate. If the batter delays play when leaving the box, the umpire shall award a strike without the pitcher having to deliver a pitch. The ball is dead and runners cannot advance.

The time clock component will force pitchers and batters to be ready once commercial breaks end between innings.

Timers, one near the outfield scoreboard and another on the facade behind home plate near the press box, will count down from 2:25 for locally televised games and 2:45 for national broadcasts.

Pitchers must throw their final warmup pitch with 30 seconds remaining. Exceptions will be made if a pitcher or catcher ended the prior half-inning at bat or on base.

A batter must step into the box between 20 and 5 seconds remaining and a pitcher must begin his motion before the clock reads zero.

These rules will be enforced through a warning and fine system, although there will be no fines in spring training or during the first month of the regular season.

Concepts for these changes were developed by a Pace of Game Committee during the Arizona Fall League season.

Other ideas from the experiment last autumn that were not implemented included a pitch clock, no-pitch intentional walks and a limit on the number of timeouts a team can call in the field for conferences.

"The Pace of Game Committee wants to take measured steps as we address this industry goal to quicken the pace of our great game," said committee chairman John Schuerholz. "It is not an objective of ours to achieve a dramatic time reduction right away; it is more important to develop a culture of better habits and a structure with more exact timings for non-game action."

As for the replay modifications, managers will not have to leave the dugout to institute a challenge. They won't have to make the slow walk onto the field to allow time for a replay review to determine if a challenge is warranted. Instead, the manager can signal to players and the home plate umpire from the top step that he is considering a challenge.

However, to challenge an inning-ending call, the manager will have to exit the dugout immediately.

Managers will still have only one challenge per game, but will retain that challenge for every call that is overturned. Last year, the manager only retained one challenge after the first overturned call.

Two challenges per game will be instituted for the postseason, regular-season tiebreakers and the All-Star Game.

Whether a runner left a base early or properly touched a base on a tag-up play will be reviewable this year, and managers must use a challenge if he believes the rule governing home plate collisions was violated.

Replay will not be used during spring training this year.