Zion Williamson is back at Duke, but just for a day. It didn’t have to be this way.

Just like that, it was Zion Williamson’s room again. He entered Cameron Indoor Stadium for the first time since his final game there, 49 weeks later, and the crowd erupted, just like old times.

Too much like old times for Notre Dame coach Mike Brey, whose team was already hanging by a very thin thread against Duke. He looked to his left down the sideline, saw the familiar face taking a seat behind the Duke bench, and absorbed both the roar and the new reality of his situation.

“As soon as he walked in,” Brey joked afterward, “I knew we had no chance of a comeback.”

Brey, as much as anyone on the outside and probably more than anyone who had to game-plan against him, appreciated Williamson’s NBA-mandated one-year basketball unpaid internship for the phenomenon it was. “Force of nature,” is the phrase Brey likes to use. It was Brey’s bad luck to be in the building the same night as Williamson again. He thought he was done with that.

So did Duke, and then that familiar sound came back, and it could only come from one place.

“I didn’t know he was coming,” said Mike Buckmire, Williamson’s buddy-movie foil a year ago. “I heard everyone start screaming and we were all looking around and of course, we see Zion walking in.”

Williamson took the opportunity of the NBA All-Star break to return to campus, but that wasn’t necessarily how he envisioned it. He declined to speak with the media on Saturday while milling about the Duke locker room afterward with Quinn Cook and Tyus Jones, but Williamson has said many times since that his decision to turn pro was not an easy one, and in a perfect world he would have come back to Duke, as much for another year on campus as for another year of basketball.

The way the system is set up, he had no choice. Coming back for another year of college would have been all risk, almost no reward for the eventual No. 1 pick in the NBA Draft.

“He can’t afford not to go,” Duke coach Mike Krzyzewski said Saturday.

Consider this: If Williamson had a choice, a real choice — if he could have, for example, signed a multimillion dollar Nike deal without compromising his eligibility as a “student-athlete” by violating the “amateur ideal” — he would unquestionably have been back at Duke, and not just behind the bench for a routine Saturday thrashing of Notre Dame.

That’s what the so-called NIL legislation being passed around the country would potentially allow. As the NCAA fights a war of attrition against the inevitable, appealing to Congress and unrolling its usual array of delay tactics, with lawsuits certain to come, don’t get caught up in the misdirection of “paying college players.” Allowing someone like Williamson to capitalize on his name, image and likeness isn’t going to destroy college sports. It has the potential to make it immeasurably stronger.

Think of the debate this way: Was college better off with Zion Williamson? Is it better off without him?

Williamson has been gone less than a year, but his shadow still looms large over the Duke campus. It just seems like he appears in every photo on the Cameron walls, dunking in one, laughing on the bench in another, holding the ACC championship trophy above his head in yet another. In at least one room, there are more of Williamson than there are of Krzyzewski celebrating national titles.

The traveling circus has moved onto the NBA, but for one afternoon, at least, it was back in Durham. There was a strange buzz in the building, a familiar buzz to those who lived through it.

“Last year was a different feel, especially at away games where people were excited to see us play, no matter where we went,” Buckmire said. “Last year was special, this year is special. Different special.”

While Duke’s new freshman in the No. 1 jersey, Vernon Carey Jr., picked apart Notre Dame like he was unwrapping a piece of candy, Williamson’s arrival heralded a second-half surge that blew the game open on the way to Duke’s fifth 30-point ACC win of the season, a school record.

After Alex O’Connell hit a 3-pointer to put Duke up 25 as the Blue Devils ran away with the game midway through the second half on their way to a 90-64 win, ESPN’s cameras caught Williamson grinning widely behind the Duke bench. Buckmire came into the game at he end to seal the win with a lay-in, an appropriate flourish with Williamson in the house.

There’s an alternate universe wherein Williamson passed up the millions on offer in the NBA to come back to Duke for a second season, which he has since said he would have liked to do. It would not have been entirely unprecedented — Andrew Luck went back for his senior season at Stanford when he would have been the obvious No. 1 pick for the Carolina Panthers after his junior year — but it would have been shocking, especially given his near-miss with catastrophe when his overstressed Nike sneaker burst at the seams against North Carolina and twisted his knee in the wrong direction.

“His shoe broke,” Barack Obama said, and the mere presence of the former president underlined just how big a deal Williamson was. “Different noise,” Krzyzewski called it.

Williamson knew he had no choice. That glimpse of disaster was a dose of reality anyone would heed, especially with the immediate riches on offer. That’s how the NCAA wants it. All or nothing. Someday, if the pace of change continues, a player like Zion might have the opportunity to actually be a student and an athlete.