The Celtics’ defense identified precisely how to defend Kevin Durant, using an assortment of looks, so much length and even more aggressiveness to minimize the superstar throughout the four-game sweep. 

Boston was less subtle in attacking Nic Claxton’s weakness: Just foul him a lot. 

Hack-a-Clax took over the Nets’ 116-112 Game 4 loss at Barclays Center on Monday night, when the Nets center missed his first 10 free throws, appearing to have less confidence with each one and inducing louder and louder groans from the home crowd. 

The Nets were 6 of 15 from the line in the first half, seven of those misses by Claxton. They trailed at the break by eight. 

It wasn’t a pure throwback to Hack-a-Shaq — Claxton typically only was fouled when he was near the hoop — but the Celtics tried to hit him hard any time he was underneath. 

Claxton went 0-for-6 from the line in the first quarter, missed one more in the second and bricked three in the third before finally hitting his 11th try. Until the final minutes of the fourth quarter when the game was hanging in the balance, the building was loudest upon Claxton swishing one free throw. 

“We all go through periods like that,” coach Steve Nash said of the 23-year-old, who actually had improved his foul shooting this season, jumping from 48.4 percent to 58.1 percent. “He’s a young player playing in a big game, and he’s a developing free-throw shooter, so to speak. 

“And so I felt for him, but that’s part of the growing pains, and he’s provided a lot for us the last couple months.” 

Somehow, Claxton still provided a somewhat productive game. The most agile and athletic center the Nets have, he was 6 of 6 from the field for 13 points with six rebounds, taking up the minutes that Andre Drummond used to receive. 

Claxton is the better defender, though he watched from the bench throughout the fourth quarter, when Blake Griffin got the bulk of the big-man minutes. 

“Proud of him no matter what,” Nash said of Claxton, who went 4 of 22 from the line in the series. “I think that he’ll grow from this.”