Major League Baseball will implement new pace of play rules for the 2018 season, Commissioner Rob Manfred announced Monday, but there will be no pitch clock this season.
After consulting with the MLB Players Association and all 30 clubs, MLB announced its slate of rules changes, among them a limit on mound visits per game.
• Pace of play rules FAQ
A pitch clock -- giving the pitcher a certain amount of time to deliver the ball -- had been one of the major proposals considered. MLB decided to defer implementation of a pitch clock, as well as a between-batter timer, in order to give players an opportunity to respond to the new rules and positively affect pace of play throughout the 2018 season.
"I am pleased that we were able to reach an understanding with the Players Association to take concrete steps to address pace of play with the cooperation of players," Manfred said in a statement. "My strong preference is to continue to have ongoing dialogue with players on this topic to find mutually acceptable solutions."
New phone lines connecting the video review rooms and the dugout will be installed and monitored, limiting the ability of teams to steal signs, which is viewed as a contributing factor to the increasing number of mound visits. Rules governing when players can and cannot leave the batter's box between pitches, instituted during the 2017 season, remain in effect.
• Players, managers react to new rules
"Players were involved in the pace of game discussion from Day 1, and are committed to playing a crisp and exciting brand of baseball for the fans, but they remain concerned about rule changes that could alter the outcome of games and the fabric of the game itself -- now or in the future," said Tony Clark, the MLBPA executive director.
Here is a breakdown of the new rules:
• Mound visits: Mound visits will be limited to six per team per nine innings. Teams will receive an additional visit for every extra inning played. Any manager, coach or player visit to the mound will count as a mound visit. Visits to the mound to clean cleats in rainy weather, to check on an injury or potential injury or after the announcement of an offensive substitution are excepted. Also, normal communication between player and pitcher that do not require either to vacate their position on the field do not count as a visit. If a team is out of visits, the umpire will have discretion to grant a visit at the catcher's request if he believes there has been a cross-up between the pitcher and catcher.

• Between-inning breaks: As has been the case since the start of the 2016 season, a timer will count down between innings from 2:05 for breaks in locally televised games, from 2:25 in nationally televised games and from 2:55 for tiebreaker and postseason games. The difference now is that at the 25-second mark, the umpire will signal for the final warmup pitch and the pitcher must throw it before the clock hits 20. The batter will be announced at the 20-second mark and the pitcher must begin his windup to throw the first pitch of the inning within the five seconds before the clock hits zero. Another important change is that a pitcher is no longer guaranteed eight warmup pitches between innings. However, he can take as many as he wants within the countdown parameters noted above. The timer will start on the last out of the inning, unless the pitcher is on base, on deck or at bat, in which case the timer shall begin when the pitcher leaves the dugout for the mound. If the final out of the inning is subject to replay, the timer begins when the umpire signals the out.
• Timing of pitcher changes: The timing clock -- as listed above -- also applies to pitching changes, and it will begin as soon as the relief pitcher crosses the warning track.

• Instant replay: All club video review rooms will now receive direct slow-motion camera angles in order to speed up challenges and the resulting review. New phone lines will connect the rooms to the dugout and will be monitored to prevent their use for sign stealing.
Summary of 2018 Rule Changes

I) Mound Visits 
1. Number
A. 2018 Championship Season. Mound visits without a pitching change shall be limited to six (6) per team, per nine innings. For any extra-innings played, each Club shall be entitled to one additional non-pitching change mound visit per inning.  
B. OBR 5.10(l). Official Baseball Rule 5.10(l), which governs mound visits by a manager or coach, remains in effect (i.e., a pitcher must be removed on the second visit by a manager/coach in an inning). 
2. Definition of Mound Visit. A manager or coach trip to the mound to meet with the pitcher shall constitute a visit. A player leaving his position to confer with the pitcher, including a pitcher leaving the mound to confer with another player, shall also constitute a mound visit, regardless of where the visit occurs or the length of the visit, except that the following shall not constitute mound visits:
A. Discussions between pitchers and position player(s) that (i) occur between batters in the normal course of play and do not require either the position player(s) or the pitcher to relocate;
B. Visits by position players to the mound to clean spikes in rainy conditions;
C. Visits to the mound due to an injury or potential injury of the pitcher; and
D. Visits to the mound after the announcement of an offensive substitution.
3. Cross-Up in Signs. In the event a team has exhausted its allotment of mound visits in a game (or extra inning) and the home plate umpire determines that the catcher and pitcher did not have a shared understanding of the location or type of pitch that had been signaled by the catcher (otherwise referred to as a "cross-up"), the home plate umpire may, upon request of the catcher, allow the catcher to make a brief mound visit. Any mound visit resulting from a cross-up prior to a team exhausting its allotted number of visits shall count against a team's total number of allotted mound visits.
II) Inning Breaks and Pitching Changes
1. Time of Break. The timer will count down from 2:05 for breaks in locally televised championship season games, from 2:25 for breaks in nationally televised championship season games, and from 2:55 for tie-breaker and postseason games as follows: 
Time Remaining | Required Action
25 seconds: Umpire signals pitcher to complete last warmup pitch.
20 seconds: Batter's announced and must leave on-deck circle, batter walk-up music shall begin, and pitcher shall complete last warmup pitch.
0 seconds: Pitcher must begin motion to deliver first pitch.
A. The pitcher may take as many warm-up pitches as he desires, but regardless of how many warm-up pitches he has thrown, he must deliver his final warm-up pitch at least 20 seconds prior to the end of an inning break or pitching change. OBR 5:07 will be revised to reflect that pitcher is not guaranteed eight warm-up pitches. 
B. The umpire shall signal for the last warm-up pitch at 25 seconds, unless a special circumstance (as described below) applies. 
C. The batter must leave the on-deck circle and proceed directly to the batter's box when the pitcher throws his final warm-up pitch.  
D. The pitcher must begin his motion for the first pitch as soon as the batter steps into the box and is alert to the pitcher; provided, however, the pitcher cannot begin his motion for the first pitch more than five seconds prior to the end of an inning break or pitching change so that television is ensured to be back from commercial break. 
2. Special Circumstances. A Player will be excused from following the time limits set forth above if the umpire determines that any of the following special circumstances are present:  
A. There is a delay in normal warm-up activities during the inning break due to no fault of the Players (e.g., injury or other medical emergency, equipment issues, playing field or grounds crew issues);
B. The umpire believes the pitcher is at a legitimate risk of injury if he does not receive additional time to throw warm-up pitches; 
C. The umpire believes the batter is at a legitimate risk of injury if he does not receive additional time to enter the batter's box; 
D. Any other special circumstances which, in the umpire's judgment, warrant allowing the pitcher to throw after the deadline. 
3. Start of Timer for Inning Breaks
A.Last Out of Inning. The timer shall start on the last out of an inning for an inning break.   
B.Close Plays/Replay Review. The Field Timing Coordinator shall delay the start of the timer if the final out of the inning is a close play that may be reviewed by instant replay. If the final out of the inning is determined in instant replay, the timer shall start as soon as the out is signaled by the umpire.  
C. Pitcher or Catcher On Base/On Deck. If a pitcher ends an inning on base, on deck, or at bat, the timer shall reset when the pitcher leaves the dugout for the mound. If a catcher ends the inning on base, on deck, or at bat, the timer will reset when the catcher enters the dugout (and another catcher must begin warming up the pitcher). 
 
4. Start of Timer for Pitching Changes
A.Pitcher Crosses Warning Track. The pitching change timer shall begin as soon as the relief pitcher crosses the warning track (or foul line for on-field bullpens) to enter the game. In the case of a pitching change that occurs during an inning break, the timer shall reset if previously started as soon as the relief pitcher crosses the warning track (or foul line for on-field bullpens).  
B.Relief Pitchers Must Promptly Leave Bullpen. Relief pitchers shall leave the bullpen promptly following an appropriate signal by their manager or coach. During the playing of God Bless America, or any other extended inning event previously approved by the Office of the Commissioner, the timer will begin at the conclusion of the song or event. 
 
5. Enforcement. Umpires shall direct players and enforce the inning break and pitching change time limits on the field. Players who consistently or flagrantly violate the time limits will be subject to progressive discipline for just cause by the Office of the Commissioner pursuant to Article XI(C) of the Basic Agreement.

III. Batter's Box Rule
The batter's box rule that was in effect during the 2017 season will remain in effect during the 2018 season.
IV. Video Replay Review
The following adjustments will be made to the video replay technology:
A. Install capability for all Club video review rooms to receive direct slow motion camera angles for the 2018 championship season; 
B. Install new phone lines connecting the video review rooms and the dugout, and monitor the communications over those lines to prevent their use for sign-stealing.