Valve has confirmed and clarified changes to the roster lock process that will be put in place for the 2017 competitive Dota 2 season. Team rosters won't be locked automatically like last year, but rather teams will remain intact, with two separate dates for dropping players from the roster and adding new members.
Managers can drop players, or players can leave a team, any time before the roster drop deadline of September 4, 2016. Any player still on a team at this time will be locked to that team until the conclusion of the next Dota 2 major, which has yet to be announced.
The second phase, where teams can add new personnel to the roster, will take place from September 4-18. Admins and managers can issue invites during this time to any player not locked to a team roster, whether a new face to the lineup or a former member of the roster itself.
These changes address concerns that many had prior to The International 6, when players like Aliwi "w33" Omar were left without a team just days before the one-time roster lock date. Team changes will be published on the Dota 2 majors team rosters page, with notable player movements highlighted.
Of special note is the rules regarding team substitutes for majors - Valve specifies that teams can issue a Substitute Player invite to any player not competing in the upcoming major once the qualifiers for said major have concluded. This could lead to teams seeking out tier-two substitutes from squads that didn't make the major, and potentially lead to more utilization of subs in forthcoming tournaments.
Dates for the next majors have yet to be released.