Several potential rule changes were recently discussed between MLB and the players union, but a pitch clock remains the primary focus.

No proposed rules change would improve baseball’s pace of action issue more than a pitch clock, which is why Major League Baseball officials prioritized getting a pitch clock for the 2019 season at a meeting with Players Association officials Monday. The union, which has been cool to the idea, said it would continue to discuss the issue with its players along with “smaller items” related to proposed rules changes that were presented Monday.

MLB officials did not press for any rules changes regarding defensive shifts, which means shifts are likely to remain unchanged for 2019.

Baseball prefers to introduce any rules changes in time for spring training games. Unlike with the pitch clock, owners do not have the right to unilaterally implement changes to defensive shifts in 2019.

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A pitch clock would have an immediate and noticeable effect on the pace of action, as has been proven in its use in the minor leagues since 2015. In MLB games from 2008 to 2018, the average time between pitches increased from 21.7 seconds to 24.1 seconds, according to Fangraphs. Add that to an increase of 4.6 pitches per game and that produces an additional 13 minutes, 38 seconds of nothingness to the average big league game over the last 10 years.

Pace of action—not length of games—is the biggest issue facing baseball as an entertainment product. Strikeouts have increased every season in that decade, adding to the burgeoning time when a ball is not put in play. The 2018 World Series averaged 4 minutes, 26 seconds between balls in play, 40 seconds more than it took during the 1998 World Series.

This is the third season MLB officials have tried to add a pitch clock. The players association has resisted its adoption for a variety of reasons; some players “don’t want to be told what to do” when it comes to preparing for each pitch while others are concerned about penalties for violating pitch clock rules. In the minor leagues, a ball is added to the count when the pitcher is in violation of the clock. Nothing drives leverage in the batter-pitcher dynamic quite like the count.

Last year MLB officials proposed an 18-second pitch clock that would be used only with the bases empty, with a 20-second clock with runners on to be added in 2019. When the players balked at the suggestion, commissioner Rob Manfred had the authority to unilaterally implement pitch clock rules for 2018. But he backed off implementation over concerns that labor relations were souring because of a slow free agent market.

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Manfred has the same three options regarding a pitch clock in these next five weeks leading to the start of spring training games:

1. Negotiate a pitch clock agreement with the players.

2. In the face of opposition from the players, unilaterally implement its use.

3. Kick the can down the road for another year, against the backdrop of another slow free agent market.

MLB officials have proposed a “soft rollout” to a pitch clock rule. Warnings would be issued instead of penalties for the first month or two and graduated tiers to the amount of time on the bases-empty clock—such as 20 seconds, then 18, then 15—would be implemented to allow players to adjust.

Major League Baseball officials have studied other ways to improve pace of action, such as the elimination or curtailing of defensive shifts and raising the minimum batters faced by a pitcher from one to three. Unlike a pitch clock, shifts tamper with the strategy of the game and affect only a small percentage of pitches. Shifts largely affect lefthanded pull hitters who have average speed or worse, which allows infielders to play deeper and cover more ground. Major League lefthanded hitters batted .275 on balls in play when facing a shift last year—23 points worse than all hitters otherwise (.298).

It was evident on Monday, however, that the only idea being treated with urgency was the pitch clock.