EAST RUTHERFORD, N.J. — The working theory on why undefeated and No. 2-ranked Duke has been so successful thus far is that each player has a well-defined role that he understands perfectly.

One Blue Devil, though actually has two distinct roles. Tyler Thornton is Duke’s backup point guard. During practice, though, he is often Seth Curry.

“When Seth can’t practice, Tyler is running his spot,” coach Mike Krzyzewski said. “Tyler is OK ego-wise, ‘OK, I’m going to do that.’ We don’t call as many plays for Tyler during the practice, but at least the other guys get into a good rhythm with an outstanding player.”

Due to a right shin injury that will bother him all season, and, last week, a left ankle injury, Curry hardly practices at all. Leading up to Duke’s Saturday game with Temple, he participated in parts of practices on Thursday and Friday. The rest of the week he tried to stay off his feet.

Yet Curry, a senior, showed no signs of rust against the Owls. He went 7 for 11 from the field, and 5 of 9 from 3-point range, for a game-high 23 points. It was the third time this season he scored more than 20 points. Curry is Duke’s second-leading scorer, averaging 16.1 points per game.

“He doesn’t practice much, so you don’t know if he is going to be sharp,” Krzyzewski said. “I thought yesterday and the day before he had good, hard practices. Once he gets going, you have to keep calling stuff for him.”

It will always be hard for Duke to have a feel for Curry’s sharpness as he will have to cope with his injury all season. The good news is, despite averaging 30.6 minutes per game and playing three straight days in the Battle 4 Atlantis tournament, his shin hasn’t gotten any worse (he didn’t play against Delaware on Dec. 1 because of that left ankle injury sustained during the Ohio State game). And even though he rarely practices, he has been able to keep his scoring rhythm.

“It’s tough,” Curry said of keeping that rhythm, “But I’m getting into a rhythm of how I’m going to practice leading up to a game. I’m still figuring it out, but I’ll let you know later.”

For now and for the foreseeable future that practice rhythm includes watching Thornton. Some former four-star recruits would probably balk at practicing for a role they won’t normally play during games.

“Me doing that is helping us get better,” Thornton said. “We need Seth to be healthy as best he can. If he can’t practice and I have to fill in for him, you know, he still comes out during the game and he performs.”

Thornton, always known more for his defense than his scoring, logged 18 minutes, three rebounds, two assists and made a 3-pointer against the Owls. Curry’s 23 points came in 31 minutes. During one stretch late in the second half when Temple cut the deficit to 13, Quinn Cook started looking exclusively for Curry, who scored seven straight points on two free throws, a jump shot and a 3-pointer.

Curry also played quality defense on Temple’s Khalif Wyatt, holding one of the Owls’ most prolific scorer to six points on 3-of-15 shooting.

“If Seth isn’t managing this injury, I think he’s really as good as any so-called two guard,” Krzyzewski said. “He’s a terrific scorer, he’s learned to be a really good defender, and he can handle, he’s gotten stronger. It’s sad that he’s had to manage this injury like he has.”

Thornton embracing his dual role has been the silver lining for Duke. And the fact that he has done it without hesitation is a bonus for a team that has emphasized chemistry this year.

“Whatever the coaches need from me, that’s what I’m going to do,” Thornton said. “So far, it’s worked out.”

Keeley 919-829-4556