Last night, there was a snag. Not that it probably would have mattered against No. 3 Duke, which put together two solid halves and rolled to an 84-68 win at Cameron Indoor Stadium.

But for Donahue, who came from Cornell as a replacement for Al Skinner, the message he sent last night was that how you practice could very well determine how you play or how much you play, no matter your status.

Starting point guard Reggie Jackson felt the full brunt of Donahue’s message. Jackson, who came in to the game as one of the premier guards in the Atlantic Coast Conference, spent the first few minutes of each half sitting next to Donahue on the bench, as Donahue started Corey Raji and Dallas Elmore, while Jackson and Danny Rubin went to the bench.

“Practice is important,’’ said Donahue, stepping carefully around the issue after the game. “And [Raji and Elmore] deserved to start. What we’re doing here is building a program and sometimes you do things that are in the best interest of the program.’’

The response from the new starters was encouraging. Raji, who began the season as a starter, responded with a solid game, scoring a team-high 18 points. Elmore, who has been productive in spurts, hit four of five shots for 10 points, which was one of the reasons why the Eagles flirted with the lead through much of the first half, before Duke pulled away to a 41-32 lead at the break.

As for Jackson and Rubin? Not so good. Rubin played only three minutes, while Jackson, who played 32 minutes, finished 3 of 11 for a season-low 7 points. After the game, he was still absorbing the demotion.

“Frustrating,’’ said Jackson, who had anticipated matching moves with Duke’s Nolan Smith, who came into the game leading the ACC in scoring and assists, and did nothing to diminish his status with a game-high 28 points and eight assists.

Jackson learned of the change at yesterday afternoon’s shootaround. When asked how he felt about the news, the 6-foot-3-inch junior paused and said, “I’m just not going to comment on that.’’

“We are just trying to build a program,’’ Donahue repeated. “Practice matters and kids who practice well get rewarded by playing time. The more I look at it, Dallas Elmore has done a really good job and so has Corey. I think both of those guys deserve to start based on how well they have done in practice over the last couple of weeks.’’

It has been a rough patch for Donahue and the Eagles (14-7, 4-3). They went into last Saturday’s game at Florida State shorthanded, as a bug forced starting guard Biko Paris to the bench. Starting forward Joe Trapani suffered from the same illness, although he played. The Eagles lost, 67-51, to the Seminoles, who have been the only team to beat Duke (19-1, 6-1) this season.

Last night was another speed bump, although the result might have been similar even if Jackson had started.

“I thought this was one of the better games I’ve seen [Duke] play,’’ said Donahue, who could do little to counter Smith’s performance and the solid play of the Blue Devils, who placed four starters in double figures. “I was pretty proud of our guys for stretches. I thought we did a good job. We didn’t make our normal plays around the rim.’’

BC was competitive in the first half, but against Duke, you need a full complement of talent playing to its full potential, and the Eagles did not have that.

It will not get easier, as North Carolina visits Conte Forum Tuesday night.

“In this league,’’ said Jackson, “there are no nights off.’’

But there are off nights, which is what Jackson and the Eagles had.

Mark Blaudschun can be reached at blaudschun@globe.com.