Getty Brad Stevens of the Boston Celtics may have more trades up his sleeve. The NBA’s new collective bargaining agreement with its so-called “second apron” rules is hitting the Boston Celtics first and hardest. After just trading for the pair two years ago in a series of moves that ended up bringing the Celtics their record 18th NBA championship , president of basketball operations Brad Stevens was forced to trade away guard Jrue Holiday and center Kristaps Porzingis , simply to keep the team