BROOKLYN – What did the Tar Heels learn from their disheartening and somewhat shocking loss to Duke in the semifinals of the ACC tournament?

First of all, they can’t play long stretches in a big game without Joel Berry, who sat out more than 10 minutes of the second half with four fouls, during which Carolina lost a 13-point lead and fell behind by seven. Duke reversed a game that had been getting away from the Blue Devils with a 29-9 run.

Despite playing for the third time in three days, Duke was energized by Berry’s departure, shooting 68.8 percent (11-of-16) over the final 15:04. As The Devils were charging, UNC’s fouls mounted, Roy Williams did not use an immediate time out and ACC Player of the Year Justin Jackson again tried too hard to shoot his team out of a tough spot.

Berry also missed the last four minutes of the first half with two fouls, when the Heels let a double-digit lead be cut in half for the second straight game. Both times, freshman guards who aren’t quite ready for prime time made crucial mistakes that gave an opponent more reason to believe it could come back in the second half. Miami did not, but Duke did in stunning fashion.

Second, Carolina won’t beat many teams from the outside and when forced to do so could not connect with any consistency. After Berry went out, Duke pushed its defense farther under the basket and made an inside offense that was dominant in the first 35 minutes almost dormant for the final 25. Kennedy Meeks, Isaiah Hicks and Tony Bradley went 13 of 18 from the floor in the first half; in the second, they attempted only nine shots and made four.

The Blue Devils basically dared Theo Pinson, Nate Britt and the stone-cold Jackson to beat them from the perimeter and their combined 6 for 26 (2-of-11 on three-pointers) could not do it. Here is where the injured Kenny Williams might have helped. Meanwhile, Duke compounded long-range shooting from the first half (5-of-9) that kept it in the game to go 5-of-8 in the second half and forge an insurmountable late lead.

Similar to the first game in Durham on February 9, Duke outscored Carolina on three pointers by 15 points and by 19 from the foul line, where the Blue Devils made 16 free throws after taking the lead to salt away the victory.

Third, momentum stop. Roy Williams did call an uncharacteristic early timeout with 10:36 left in the game after his team had lost all but two points of its once double-digit lead. But it wasn’t early enough to correct what he later termed a lack of movement that turned a 55 percent shooting offense in the first half into an anemic 29 percent nightmare in the second.

The turnaround violated a long-time Carolina tenet dating all the way back to Dean Smith of not taking what the other team gives you –  in this case, the outside shot – but doing what WE want to do. The missed shots gave Duke an 18-8 advantage on the defensive backboards, triggering a 60-percent shooting half for the Blue Devils who made every big shot to turn the tide and put the game away. Duke is not a team that you can help get its offense rolling.

The game turned around on two plays – a driving dunk by Jason Tatum that cut the deficit to 11 and prompted a trademark timeout by Mike Krzyzewski, who uses the ploy after a big play to gather his team for a late push. Sure enough, after a missed jumper by Britt, Duke’s big three combined for a four-point play that brought Duke to within seven. Tatum missed a jumper and in a scramble for the rebound Grayson Allen batted it over to an open Luke Kennard, who buried a three-pointer from the corner as he was fouled by a later-arriving Britt.

Two minutes later the game was tied and five minutes after that, the Blue Devils owned a seven-point lead that Berry’s return could not reverse. Duke was up by 13 when Williams cleared his bench in final 20 seconds and Stilman White hit a smoother three-pointer to make the final margin 10. It was White’s second three-pointer in four attempts this season, making him – statistically at least – the best three-point shooter on the team.

Duke’s big three, meanwhile, hit 8 of 12 triples, including Allen’s four in the first half that Krzyzewski claimed kept his team from falling behind by 20. “They were playing a lot better than us than the score indicated,” Coach K said. “We were getting ready to get knocked out and Grayson saved us.”

Duke got off the matt to rally and, hopefully, teach its arch rival some valuable lessons moving forward. Because, from here on out, it’s one and done.