So, just as a reminder how free agency works, since a refresher seems needed. Teams are not allowed to reach out to free agents until 6pm, and are not to announce anything before midnight tonight, except with your own free agents. So while it may seem like Brad is doing nothing, if we actually heard a credible rumor of the Celtics reaching out to a player, that would mean the Celtics broke the rules. So you should not want to hear anything for another few hours.
All the announcements so far have been players remaining with their original teams before hitting free agency.