MLB is implementing a July 31 trade deadline for the 2019 season, per a new report out from Jeff Passan. Passan says that MLB and the MLBPA have agreed to several changes, including going to a 26 man roster in 2020, beginning discussions on changes to the CBA immediately, and eliminating post-July 31 waiver trades:
While July 31 has been the kind-of official trade deadline in MLB, teams could make trades after that date involving players on the 40 man roster who had cleared revocable trade waivers. Players traded after July 31 and before September 1 were still playoff eligible, which meant that teams in the race could make minor moves to pick up a veteran journeyman for the stretch run (such as when the Rangers traded for Wil Venable in 2015 or Miguel Gonzalez in 2017), or, occasionally, add a quality, high-dollar player whose contract kept other teams from putting in a claim (such as the Astros acquiring Justin Verlander in 2017).