Seth Allen, shown earlier this season against Florida State. (Jonathan Newton/The Washington Post) Seth Allen, shown earlier this season against Florida State, didn’t have much of an impact against Duke. (Jonathan Newton/The Washington Post)

Immaturity has long been an issue for the Maryland basketball team, especially among its freshmen. Jake Layman was disciplined before winter break for failing to take care of his academics. Charles Mitchell missed the first half against Miami for an “in-house” disciplinary issue. Against Duke, it was Seth Allen’s turn.

Allen was benched for the entire first half of an 84-64 loss to the Blue Devils after arriving late to a team meeting, Coach Mark Turgeon said during his postgame news conference. But he played down the incident’s severity, just as he did with Layman and Mitchell.

According to Turgeon, the team voted on Allen’s punishment, settling on a 20-minute benching. He ended up playing 10 minutes Saturday afternoon, missing a three-pointer and making a driving layup through traffic. He had two rebounds, two fouls, zero assists and zero turnovers. Allen had provided a spark on the wing throughout ACC play, and entered as Maryland’s third-leading scorer during conference games.

“Don’t want it to become chronic,” Turgeon said. “The thing that’s holding our team back, and I’ve been saying it for about a month, is immaturity.”

Perhaps Duke provided a mini-lesson for the Terrapins. Rasheed Sulaimon posted a career-high 25 points, but the Blue Devils were sparked in the second half by senior Mason Plumlee, who seemed to take Duke’s recent loss to Miami personally, even sending a message to his teammates by not jumping for the opening tip.

Such veteran leadership and production, Turgeon said, is missing from his team. Senior forward James Padgett’s minutes have dwindled, and he’s hardly an offensive force. Graduate student Logan Aronhalt is a role player, inserted to break zones and provide instant offense. He possesses the necessary wisdom and self-awareness, but only transferred to Maryland this offseason. Pe’Shon Howard, the team’s only healthy junior, has struggled offensively in ACC play, providing more intangible qualities like defense and tempo dictation above anything else.

“We don’t have a Mason Plumlee for our young kids to lay on or rely on, or a Seth Curry,” Turgeon said. “We don’t have that. We’re not going to grow up as quickly as a Duke team’s going to grow up with young kids. We have to learn sometimes the hard way.”

Even without Allen, the Terps still trailed by only eight points at halftime. But a defining run never came, as Duke slowly extended the lead, never allowing Maryland to come within single digits after Plumlee hit the back end of two free throws with 11:36 left.

“I was pretty pleased [in the first half], but I was wishing we got the lead, but it didn’t happen,” Mitchell said. “I was pleased with our effort on the offensive and defensive end. I wish we would have had Seth. He would have given us better offensive and defensive presence too.”