PORT ST. LUCIE — The August trade, which was instrumental in the Astros winning their first World Series in 2017, is on life support.

MLB and the Players Association are inching closer to agreeing to a series of changes, some for 2019 such as the abolition of the August waiver trade period some for 2020, all with the understanding that after this season begins the sides will continue to discuss economic issues that concern the union.

The negotiations are fluid, nothing is finalized and distrust still exists on both sides. But there is a sense of common ground and momentum that has created some optimism that what both sides see as win-win scenarios could be finalized in the coming days.

The most immediate impact would be — if this deal is completed — the elimination of August trades. The hope is that will lead to fewer teams continuing to sell off players and, thus, fewer clubs in tanking mode over the final two months of the season.

Through July 31, teams do not need to pass players through waivers to complete a trade. But after that deadline, players had to pass through waivers. If the player was claimed, only the two teams involved could make a trade. If the player passed through waivers unclaimed, any team could trade for him through Aug. 31.

Most famously, just before midnight Aug. 31, 2017, the Astros obtained Justin Verlander from the Tigers and the righty served as Houston’s ace en route to a championship. The Yankees obtained Andrew McCutchen on Aug. 31 last year. In 1992, the Blue Jays acquired David Cone from the Mets to finalize their first championship team. In August, 1987, Detroit picked up Doyle Alexander from Atlanta and the righty went 9-0 down the stretch to help the Tigers nip the Blue Jays for a division title. The cost was a mostly unknown pitching prospect named John Smoltz.

Also for 2019:

— The number of mound visits for nine innings would drop from six to five. A joint committee would decide whether to go to four for 2020.

— Between-inning breaks would drop to two minutes, both nationally and locally, and to 1:50 in 2020. Currently, national breaks are 2:25 and local 2:05.

— Financial rewards for All-Star participation/events would rise. As The Post reported last year, MLB was willing to improve the monetary benefits for All-Stars in exchange for a system MLB thought would create greater interest: an initial wave of voting, as has been done in the past, then a cutdown in mid-June to the top three vote-getters and the beginning of a new election process to decide the starters. MLB hoped the players would take to social media to elevate interest in their candidacies. The union rejected that proposal.

For 2020:

— Rosters would go from 25 to 26 players, no more than 13 of whom could be pitchers. In September, rather than expand to up to 40, teams could be allowed to go to 28, no more than 14 of whom could be pitchers. Players who are optioned off the 28-man roster following the end of the minor league season would continue to accrue major league service time.

— The Injury List term would go to either 12 or 15 days for pitchers as a way to try to get teams not to play roster shenanigans with dubious pitching injuries.

Commissioner Rob Manfred could have, by rule, installed a pitch clock for the 2019 season. But it would not have received the blessing of the players and without agreement the decision was made to table a pitch clock until after the conclusion of the current CBA following the 2021 season.

The sides also agreed to work through these more immediate matters that they see as win-win with the promise that they will discuss issues most pertinent to the union, namely the slowed free-agent market, service-time manipulation and tanking. If the sides are able to come to agreement on these larger economic issues, the hope would be to extend the CBA beyond 2021.

The sides have amended the CBA in progress in the past for items such as drug testing and a domestic abuse policy. But they have never done so before on major economic issues. So there remains concern — especially because significant tension exists between the parties — whether they can find common ground in these areas.