To add to what others said, towards the end of the game, even though they were headed for a certain loss, the Suns kept fouling Celtic players in order to stop the clock and preserve possessions, in which they would immediately give Booker the ball to try to score. The Cs didn't want to foul (because they wanted the clock to run) so they had to guard him very loosely. Thus Booker was able to tack on a bunch of slop time scores at the end.
The whole thing was an embarrassing joke and by that I don't mean I was embarrassed by the Celtics defense. It was embarrassing to watch the Suns, which is a franchise which has some great basketball history, stoop to such embarrassing tactics to try to create a dubious 'achievement'.