Trying to determine when a college player should leave for the NBA can be a hit-or-miss proposition. How is his draft stock helped or hurt by his decision? How much can he improve on his weaknesses if he stays in college versus going to the NBA? Can he enter the league as a better player if he stays to play another year of college basketball?

While the 2016 NBA draft will be chock full of freshmen as usual, here are four college players who made that difficult decision to return to school in order to improve their draft status. I offer some ideas on areas where each can improve to make that happen:

Kris Dunn, Providence Friars (Jr., G, 6-3, 205)

Dunn was chosen the Big East Player of the Year and Defensive Player of the Year, becoming the first guard in the league’s history to accomplish that feat. In fact, he dominated on both ends, averaging 15 points, almost 6 rebounds, almost 8 assists and nearly 3 steals per game.

Like many, I was surprised Dunn decided to return to Providence for his junior year. And it is not because he doesn't have areas he could improve on. He does. But more importantly, I thought that in his first completely healthy season as a Friar after two shoulder surgeries, his draft stock was rising.

But he returned, and while Dunn will be on many preseason All-America teams, there are some areas where he can become more ready for the NBA.

First of all, it is critical he improves his shooting. NBA point guards who can’t make open shots shrink the floor for their teammates. And while it might be a major question mark for Dunn, there is hope. His 35 percent shooting from deep was not bad but was part of a small sample size -- he made 27 of 77 attempts. And he made 42 percent of his 2-point jump shots last season.

Dunn needs to spend the summer in the gym honing that jump shot, but there is more that he can improve. He has the size and strength to attack the basket, but he has work to do in that area. While he can get to the rim, he is not a high-percentage finisher. He is a double-pumper and avoider of contact, and it showed in 49 percent finishing at the rim in nontransition plays.

Finally, for a point guard who averaged seven assists per game, Dunn can sometimes pass erratically and it shows in a 25 percent turnover rate. It is critical he shows NBA teams next season that he is a good decision-maker and will be a low-mistake player.

I have no doubt Dunn can be a dominant college player next season, but pointing out areas of weakness is probably something the Friars' coaching staff will echo this summer.

Jakob Poeltl, Utah Utes (So., F, 7-0, 235)

Austria has never produced an NBA player, and the 7-foot Jakob Poeltl likely will be the first if next season goes as planned. After a surprisingly good freshman season at Utah, he thought about leaving for the NBA and would have likely been taken somewhere in the middle of the first round. Ultimately he elected to return to school for his sophomore season.

While Poeltl’s size and agility were impressive attributes this season, facets of his game can improve so he is more ready for the next step. He has the added benefit of playing for a former NBA player, Larry Krystkowiak.

First of all, Poeltl must develop a low-post go-to move and a countermove he can rely on, allowing him to play with his back to the basket and broaden his offensive arsenal. He already has excellent hands and footwork in the low post.

Last season, more than half of his baskets came on energy plays consisting of offensive rebound putbacks, cuts to the basket and points in transition. Watch him on the fast break and you will see he catches passes as if he were a Venus flytrap. He is an excellent athlete for his size.

And as is the case for most college post players, once Poeltl becomes a legitimate scoring threat inside, he will need to improve on his passing out of double-teams because he will see them often. That means his court awareness will need to improve as well.

Finally, if Poeltl becomes more of a threat in the low post, he will have to improve on his anemic 43 percent free throw shooting. If you watched him carefully last season, you noticed that he rushed shots in the paint because it seemed as if he were afraid to get fouled.

While Utah has graduated All-Pac 12 guard Delon Wright, who will likely play in the NBA next season, I fully expect the Utes to play through Poeltl effectively on the offensive end of the court. It will complement the elite rebounding and shot-blocking he already provides his team. He’s already one of the best returning players in college basketball.

Buddy Hield, Oklahoma Sooners (Sr., G, 6-4, 209)

Because the NBA is a league of role players (minus the 25 or so superstars), Oklahoma’s Big 12 Player of the Year Buddy Hield has a chance to find a role as a 3-point shooter and, potentially, a wing defender after his senior year at Oklahoma.

There are few in college basketball who display more confidence and play with as much flair as Hield does. In the opening game of his junior year at Oklahoma against Southeastern Louisiana, he made 7 of 7 shots from behind the 3-point line. And while he ended his junior season in an 11-for-40 shooting slump from behind the arc, he built a solid résumé of 13 games scoring more than 20 points.

What NBA teams will like is that Hield was not highly ranked coming out of high school but got better each season at Oklahoma. He has an incredible appetite for work, so he has one more year to make real improvements in areas that can potentially impress NBA teams.

The 6-foot-4 Hield can help himself in improving his ballhandling and passing in order to create more scoring opportunities for himself and his teammates. He is not likely to play point guard in the NBA, but moving the ball effectively can enhance his stock.

What makes Hield an interesting prospect is his scorer’s mentality and great confidence. But his confidence hurts him in the number of contested, low-percentage shots he takes. He will have to learn to be more efficient when he gets the opportunity. While less than a fifth of his shots were midrange jumpers, he made only 32 percent of those shots.

Although Hield will be undersized at the NBA shooting guard position, he should be able to become a good defender, if not ever a defensive stopper. His energy level is very good; he has high character; and his “give a damn” meter is high.

Melo Trimble, Maryland Terrapins (So., G, 6-2, 175)

There is so much to love about Melo Trimble. He was one of the most dynamic freshmen in the country last season in leading the Terrapins to a 28-7 record. He scored from everywhere on the court, got himself to the free throw line a lot and ran his team like a veteran.

There’s no reason he shouldn’t pick up right where he left off this coming season. But if we are talking about his NBA prospects after his sophomore season, there are two areas he must address: defense and decision-making.

Let’s look at Trimble’s strengths first. He is a major league shooter who is equally effective off the catch and off the dribble. And he not only makes 3-point shots at a high rate -- he shot 41 percent as a freshman -- he made a lot of them, averaging almost two a game.

And, as Trimble's a below-average-sized NBA point guard, it helps immensely that he drilled about 38 percent of his 2-point jump shots as well. Overall, he connected on only 55 percent of his shots at the rim. So the midrange game for him is critical. While I don’t expect him to be an elite finisher at the rim in the NBA, he deserves a lot of credit for getting to the free throw line 240 times last season.

But let’s get back to my concerns. Trimble’s defense on and off the ball must improve. His alertness is average; his ball pressure can be much better; and his ability to fight through screens is not optimal right now. There is no reason that he should not be a more disruptive defensive player.

In this regard, Trimble reminds me of former Michigan point guard Trey Burke, who was the darling of the Big Ten and was selected No. 9 in the 2013 NBA draft. After only two seasons with the Jazz, his career hangs in the balance because of his weak defense.

From a decision-making standpoint, Trimble must be able to take care of the ball better and deliver more on time, on target passes. Again, his size affects him negatively, especially in screen-and-roll plays because he must be able to see over bigs who defend with urgency.

Overall, I thought Trimble made a wise move returning to Maryland for his sophomore season. He not only should be one of the dominant offensive players in the country, but his team has a legitimate opportunity to get to the Final Four. Given the great opportunities that lie ahead for him after college, however, there is work to do this summer.