Duke has played games where it displayed a more traditional player rotation and others where Hall of Fame coach Mike Krzyzewski has subbed five guys in as a group.

Postseason play, more specifically the NCAA Tournament, means things could change again, particularly with perimeter players.

Heading into No. 8 Duke’s NCAA Tournament game with Mercer on Friday (12:15 p.m., WRAL), Blue Devils senior guard Tyler Thornton knows how things can be during the season’s most important games “We are going to rotate guys,” Thornton said. But at this time of the year if you are playing well coach is going to keep you on the floor. If a guy is doing something really well that’s helping the team, coach is going to keep you on the floor because we don’t get another day.”

Duke learned the harshest lesson of all about being denied another chance to play when Thornton was a sophomore. In the 2012 NCAA Tournament, 15th-seeded Lehigh upset the No. 2-seeded Blue Devils 75-70 at Greensboro Coliseum.

Thornton started that night, contributing seven points, six assists and only two turnovers in 33 minutes before fouling out. But Duke had more turnovers (13) than assists (12) that night. Defensively, Duke struggled to contain Lehigh guard C.J. McCollum, who scored 30 points while making 10 of 11 free throws.

Lehigh turned the ball over just eight times.

It didn’t matter that Duke had the superior athletes — starters Austin Rivers, Miles Plumlee, Mason Plumlee all became NBA first-round draft picks — and a Hall of Fame coach. Lehigh beat Duke on the perimeter and won the game.

That game is just one example of how important perimeter play is when NCAA Tournament time arrives.

“The ball is in the guard’s hands,” said Duke associate head coach Steve Wojciechowski, a former Blue Devils point guard himself. “There are so many important decisions in all games. But it’s magnified in NCAA Tournament. Every possession is so important.

“A lot of times with big guys, those guys are finishers. The better your guard play the better chance you have to win.”

The game with Mercer figures to be Exhibit A in that debate. The Bears (26-8), who won the Atlantic Sun Conference Tournament, start five seniors. Their best player is point guard Langston Hall, the conference player of the year who averages 14.7 points, 5.6 assists and 1.5 steals per game.

“Our guard play on both ends of the court will be hugely important,” Wojciechowski said.

Thornton has started the last 14 games for Duke and 52 games in his career. Krzyzewski has rotated sophomore Rasheed Sulaimon, redshirt senior Andre Dawkins, junior Quinn Cook and, a few times, freshman Matt Jones, through the lineup.

All, with the exception of Jones, has NCAA Tournament experience. Sulaimon started all four games during Duke’s run to the NCAA Tournament Elite Eight last season.

As a freshman in 2010, Dawkins played in all six games as Duke won the NCAA championship.