Duke’s Trevon Duval drives against North Carolina’s Joel Berry II during Friday night’s ACC semifinal. (Al Bello/Getty Images)

Sally Jenkins

This Atlantic Coast Conference tournament has been a philosophical argument as much as a physical one, pitting just-passing-through juveniles against veterans. If the semifinal confrontation between Duke and North Carolina established anything, it was that seniors can play silly too.

Partly it was the brutal physicality of the game that made it deteriorate at the end. For 35 minutes the Tar Heels and Blue Devils went at each other like one of those superhero clashes where they try to hurl each other to a far planet. “A disjointed game,” Duke Coach Mike Krzyzewski called it. Carolina Coach Roy Williams said, “Some of the weirdest stuff I’ve ever seen.” When the Tar Heels built a 16-point lead, it was tempting to conclude that age was the difference, that the Tar Heels were simply more grown and had more know-how. Then came those last 5 minutes and 34 seconds, when suddenly the vastly mature defending NCAA champions couldn’t handle the ball or make a shot, with five straight turnovers and no field goals. Somehow, they found a way to survive it — barely.

“It’s just another thing I can say I’ve been through,” Tar Heels senior guard Theo Pinson said.

The Blue Devils were the standard-bearers of the one-and-done-rule, Marvin Bagley leading a quartet of freshmen who are using Duke as their lily-pad on the way to the NBA. The Tar Heels were the epitome of success-by-seniority, with their backcourt of two 22-year-olds in Pinson and Joel Berry II.

The final margin, 74-69, didn’t necessarily prove the enduring superiority of either philosophy. As it happened, the Tar Heels’ most stalwart performance might have come from freshman power forward Garrison Brooks, whose magnificent flexing in the post kept Bagley from taking over the game. And the lamest play all night came from the Blue Devils’ senior Grayson Allen, with his butt-check flagrant foul at the close of the first half.

This is not to say that the Blue Devils aren’t in a race against time. Despite the obvious NBA-readiness of the slithering shape-shifting Bagley, they’re a team that has never seemed fully cooked. Rarely has Krzyzewski had to so recalibrate and scale down his demands, typified by the zone defense they play out of necessity. Still, there is a fascination in watching a team that is such a project. You could sense their latent power, how monstrously good they might become, when they went on that 13-0 run to cut it to three with 52 seconds left.

“It’s about practice and finding our team,” Krzyzewski said earlier in the week. “When you start a book, do you already know the ending? No. Or else you wouldn’t read the book. . . . And so it’s part of getting to know them, not just individually but how collectively they make each other better. . . . We’re just growing.”

It’s not that Carolina totally rejects NBA-ready high schoolers. Williams tried hard to recruit Kevin Knox and lost him to Kentucky. “Everybody likes talent, and I do, too,” Williams said. But he has chosen to chase fewer of them, on the whole, preferring slower-developing teams.

“I’d love to have one or two of those guys, but I like some other guys that I get to enjoy and get to know even better, and are not there only eight or nine months, or something like that,” he said. “It’s a smaller philosophy difference . . . I would struggle — I’m old-fashioned. I’m old-school . . . I like to have some guys that can stay and have a special relationship with for a long time.”

Still, as Williams could tell you, having full-grown players doesn’t guarantee they’ll always play reliably. The Tar Heels’ spasms of brainlessness in this tournament have provoked him to sub out the entire starting five, and to try to rip his suit coat in half. The clothing tantrum came in their second game against Syracuse, when Pinson jacked a quick shot late in the game instead of running down the clock like he was supposed to.

“He thought it says in the Constitution of the United States that he had the right to shoot the ball,” Williams said sarcastically. When Pinson missed, Williams got so livid he bared his teeth, flapped his coat around, and began trying to tear it in two at the seams. Afterward he said the reason he went for the coat was because he couldn’t lay his hands on Pinson.

“I talked to the guys about how to rip a jacket in half, and how I did not do it properly,” he said. “I started around the collar where it’s folded over, so the material is twice as strong. If you really want to rip a jacket in half, start at the back at the bottom where it’s already split. Now you learn something.”

What exactly makes a team of upperclassmen a better bet than a cluster of pro-caliber freshman? It’s not that they have more composure, which they don’t always. It’s that their skins are thicker. The Tar Heels were willing to force the action more, and live with the consequences.

They courted humiliation in those last five minutes. Luke Maye lost the ball off the baseline driving to the basket. Pinson dribbled into a trap, and bobbled the ball out of bounds with 11.8 seconds left, giving the Blue Devils a chance to tie. “You can’t make that crap up,” Williams said. But Allen’s forced three-point attempt never found iron — say what you will about Allen, but he too forced the action and you had to respect that he has spent four years pulling triggers in a rain of boos. And it was his foul of foul of Pinson on the other end that was the grand determiner. Now it was Pinson’s turn to be the hero, or a double goat, at the free-throw line.

“I made a big time turnover that I needed to make up for, and I’m going to be honest, I was like, you’re making these two free throws,” Pinson said. “Like, you just almost blew the game for your team, so you have to make them.”

Spoken like a senior.