When a team signs a free agent it is not allowed to trade that player for the period of time that is greater between three months or the arrival of Dec. 15. This is because the NBA and the players association do not want teams to sign players and immediately trade them if they later feel they made a mistake. Even though this season has already seen three trades, from the Jimmy Butler blockbuster to the Cavaliers selling off veterans, trade action really picks up when the no-trade restriction ends on Dec. 15.