DUNEDIN, Fla. — The winds of change are coming to baseball this year and next.

Major League Baseball and the Players’ Association on Thursday jointly announced rules changes, some of which will go into effect this season and some of which won’t begin until 2020.

The biggest tweaks that will affect the game on the field won’t start until 2020.

The most controversial is a three-batter rule for starters and relievers.

A pitcher will have to face at least three batters unless he finishes a half-inning or is injured while on the mound.

The intent of this and most of the other changes is to speed up the game. The parade of one-batter relief appearances that has slowed an already slow sport to a crawl will end after this season.

Changes that will go into effect this season include a proposed shortening of the between-innings break from 2:05 to 2:00 for local games and from 2:25 to 2:00 for national games (although the statement from MLB and the MLBPA noted that these changes are “subject to discussions with broadcast partners,” who won’t want to lose commercial time without compensation.)

Also new for 2019: Mound visits will be reduced from six to five. There will be one trade deadline of July 31, after which no trades can be made. So say goodbye to August nonwaiver trade deadline deals.

The commissioner’s office previously announced a change for this season in which managers will be required to send lineups to MLB 15 minutes before they are released to the public.

This is meant to “reduce integrity risks” now that the Supreme Court has legalized sports gambling in all 50 states.

Also beginning this season, fan voting for the All-Star Game will be divided into two rounds (with the second dubbed “Election Day” by MLB in an attempt to drum up interest).

Home Run Derby prize money will be increased to $2.5 million, including $1 million for the winner.

In 2020, rosters will expand from 25 to 26 from the start of the season until Aug. 31.

This season will be the last with a 40-man roster expansion in September. In 2020, each team will expand its roster to 28 beginning Sept. 1. A joint player-management committee will set a limit for the number of pitchers on a roster.

Also, MLB agreed not to implement a 20-second pitch clock during the length of the collective bargaining agreement, which ends after the 2021 season.

MLB had been experimenting with a pitch clock in spring training, but the union was very much against it.

The parties also agreed to discuss a renegotiation and extension of the current collective bargaining agreement. The union is upset with the slow pace of the free-agent market in the last few offseasons and wants changes to the current system.

The union has also proposed bringing the designated hitter to the National League, but no mention was made of that on Thursday.

Other changes:

Position players will be prohibited from pitching through the ninth inning unless the player’s team is winning or losing by six or more runs when he takes the mound.

The injured list and option recall minimum period for pitchers will increase from 10 days to 15 in 2020, an effort to slow the use of relievers by teams who shuttle pitchers between the majors and minors.