I think that a quick look at the stats from the first half and the second half will make it clear (click the pics to seem extended) :
First half

Second half

As you can see, the offensive boards didn't kill us in the second since the Hawks got 7 of their 9 in the first half.
However you can see that Boston got only 12 free throws in the second half, and Atlanta 20 (!), Boston got called 11 more fouls, Atlanta for 10 (but non shooting fools for the most part) which makes a total of 21 for Boston and 16 for Atlanta.
Final differential in free throws : 33 to 18.
Crawford, who was struggling in the first half (0/4) made 4 of 9 shots in the second half but benefited from 8 free throws (while he attempted the exact the same shots in the first and got nothing).
And the boxscore doesn't show the non calls from the refs (illegal screens, fouls, traveling...)