When asked about his team's rebounding since making the change against Duke on Feb. 13, he said: "There's no question that is still something we're concerned about."
Moments later, he added: "It's still a huge, huge question for us."
There's reason for concern. UNC has outrebounded its opponent just once in the past eight games after grabbing more rebounds than its opposition 17 times in its first 23 games.
North Carolina's plus-9 edge on the offensive glass in Saturday's loss to Duke broke a streak of five consecutives games in which its opponents had pulled down more offensive rebounds. UNC had been outrebounded on the offensive boards six times in its first 26 contests.
On Feb. 10, UNC ranked 55th nationally in rebound margin (plus-4.7). The Tar Heels have since fallen to 92nd (plus-2.9) due to a minus-2.1 rebounding margin over their last eight games.
Those negatives, however, pale in comparison to the positives of going small.
"Why do you make changes?" Williams asked rhetorically on Monday. "Because something wasn't working as well. Well, it wasn't working as well defensively and rebounding with the two big guys and scoring. All right, so which one can you help?
"We felt like we could help the scoring. We also felt like we might be able to help parts of the defensive play because we could put more pressure and maybe turn them over a little bit more. And I think we did score better and we did defend and turn them over a little bit more."
While Williams acknowledged that he still sees better rebounding effort when he inserts two bigs into the lineup, wings Reggie Bullock and P.J. Hairston have effectively negated some of the concern with their work on the boards. The duo is averaging 14.4 combined rebounds, including 5.3 offensive boards, since the lineup change.
Forward James Michael McAdoo, however, has struggled against opponents' 5-men in recent weeks. After averaging 9.0 rebounds per game in the first four games of the new look, he's only managed 13 total rebounds over his last four outings.
Williams has emphasized a group approach in attacking the glass, according to freshman guard Marcus Paige.
"I try to get in there and mix it up a little bit and Dexter as well," Paige said. "Obviously I have to get back on offensive rebounding, but we always say its got to be a group effort if we're going to have four guards in and try to rebound against other teams that are bigger than us. So we've tried to get in there and mix it up a little bit more, but it's not easy to do."
Previous Tar Heel teams could outscore and outrebound their opponents at the same time. UNC doesn't have that luxury this season, although Williams has seen enough over the last month to know how he plans to proceed.
"We're going to stay with P.J. as the 4-man, there's no question," Williams said. "But during the course of different games, we might play big guys more. It's getting too much credit, because our players are the ones that did it – but that lineup has been better for us, so we'll stick with that right now.
"But Ol' Roy is not going to be small for the rest of his coaching career, I can tell you."