Duke Basketball: 1 Area Each Returning Blue Devil Must Improve in 2015-16

Read any projection about Duke's chances of repeating as national champions in 2015-16, and two major pieces of information will be taken into account: addition and subtraction.

But no problem can be solved without an equal sign.

Duke lost four starters from this past team, yet because Mike Krzyzewski landed the No. 1-ranked recruiting class (per 247Sports) there's not much dropoff expected from the Blue Devils. This is because the strength of those being added to the program offsets much of what's been lost.

What about the holdovers, the guys who were part of last season's team but didn't graduate, turn pro or transfer to another school?

Duke returns four players who saw meaningful minutes in 2014-15 as well as transfer Sean Obi, who sat out last season after coming over from Rice. Each of these returners is expected to contribute to the title defense, but each has something they must improve on before they can be counted on as more than supporting cast members.

Sean Obi

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Body control

At 6'9" and 270 pounds, Sean Obi made for quite an imposing figure on Duke's bench last season. But because he'd transferred from Rice, that was all he was able to do during games. Practice was where Obi had to get his energy out; then once the real action started he had to sit back and be a cheerleader.

That's going to make Obi liable to come out like a ball of fire when the 2015-16 season gets underway, especially if he's unable to crack the starting lineup and has to fight for minutes off the bench. Bleacher Report's Glynn Williams projects Obi as a starter, but a lot will depend on how preseason practice goes and what type of lineup Mike Krzyzewski wants to go with.

In order for Obi to be involved, though, he needs to make sure to properly use his size instead of having it be a limitation.

During his one season at Rice, Obi averaged 11.4 points and 9.3 rebounds per game but also three fouls per contest. He had at least least four fouls in 13 of 30 games, fouling out four times.

Grayson Allen

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Shot selection

The forgotten member of Duke's star-studded 2014 recruiting class, Grayson Allen was the only one of the quartet who didn't start as a freshman. In fact, he didn't even get into four games, while in 11 others he logged five or fewer minutes.

Yet in just 9.2 minutes per game, Allen still managed to jack up 106 shots including 52 three-point attempts. He was 42.5 percent from the field and 34.6 percent from outside, which were decent numbers but might have been better had Allen thought first and shot second.

We saw what Allen is capable of during the Final Four, when he had 25 points in the two games in Indianapolis. He had 16 points in 21 minutes in the title game against Wisconsin, including eight in a 70-second span during the second half that sparked Duke's comeback to the championship. Allen's aggressive play also got him to the line quite often as a freshman, but he was often out of control when not getting the call.

Assuming Allen is able to beat out Luke Kennard—or at least share the 2-guard spot with him—he will need to be more selective with his shots in order to stay on the court.

Matt Jones

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Contribute beyond scoring

Matt Jones got moved into the starting lineup late last season when Duke decided to go smaller, moving Justise Winslow to the 4 and running three guards out there on a regular basis. Jones responded by averaging 7.8 points per game, up from 6.0 for his season average.

But Jones struggled during the NCAA tournament, ending his sophomore year on a down note. He's likely to return to a reserve role in 2015-16, and with a potentially deeper team this season he's going to be looked to for production in other ways besides scoring.

Jones had only 39 assists in 841 minutes of action, and with Duke having plenty of other offensive options he's going to be used more as a distributor than a scorer.

Amile Jefferson

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Become a leader

After three seasons of being a key contributor, but one who wasn't considered a go-to guy in most situations, Quinn Cook took on the role of veteran leader last year as Duke's lone senior. This transformed his outlook on the game and thus turned him into the Blue Devils' unsung hero for his ability to lead, guide and produce.

Amile Jefferson isn't going to be asked to do much of that last part, but as one of two seniors in Duke's rotation in 2015-16 he will be called on to mentor the latest crop of newcomers and underclassmen.

Jefferson averaged 6.1 points and 5.8 rebounds in 21.3 minutes per game last year, shooting 63.1 percent but losing his starting job in mid-February to Matt Jones. Jefferson never showed any concern for this switch, and in a way got a jump start on what's going to be his role as a senior.

Marshall Plumlee

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Be more aggressive offensively

When Marshall Plumlee got an opportunity to score during his limited playing time last season, he often didn't hesitate. This resulted in the center shooting 76.2 percent from the field, but that figure must be tempered by knowing he only attempted 42 shots in 375 minutes of action.

Usually Plumlee was in the game to spell Jahlil Okafor during the first half or during garbage time, when there was no need to be taking shots in anything other than surefire situations.

There's no Okafor anymore, though. And while Plumlee isn't going to be starting as a senior, the 7-footer is poised to get more minutes than the 9.6 he had in 2014-15. Duke's frontcourt rotation will consist of Plumlee, Obi and freshmen Chase Jeter and Antonio Vrankovic. Obi and Jeter will get the most minutes, but Plumlee could be first off the bench in many situations when a big body is needed inside.

Plumlee only took three or more shots in four games last year, but that included going 5-of-6 against Robert Morris in the second round of the NCAA tournament and making all six field goals against North Carolina State during the ACC tournament. More of that aggressiveness will serve Plumlee well in his final season.

Follow Brian J. Pedersen on Twitter at @realBJP.