Evil Geniuses, Team Secret and OG declined the invitations to DreamLeague Season 6 because the event is scheduled too close to The Boston Major.
DreamLeague announced participants of the new season in September, and no one knew where the event would be hosted. Two days ago, Valve announced The Boston Major schedule (December 3-4), and DreamLeague LAN-finals are scheduled on November 25-26.
As a rule, teams have every day training for a couple of weeks before the event starts. The trainings are held at the bootcamp within the same time zone of the tournament. If the teams join both upcoming events, they will have only 6 days between two LAN-finals and this is not enough to have a rest and get proper trainings.
The organizers still did not comment the decision of the teams and did not announce the names of new rosters that will replace them. DreamLeague Season 6 start is scheduled on October 11, and it means that only a few days are left to get confirmation from new participants.