Most NBA teams have their starting lineups in place well before training camp. The decision is made as much by management as the coaches. It’s hard to bench guys taken high in the draft or with big guaranteed contracts. There are office politics in NBA locker rooms, just like any other workplace. The difference is how quickly they change. Roster turnover makes the dynamic different every season. Even in the rare situations when the entire team is back, some players have gotten better while others have gotten worse.

An NBA head coach has two jobs. They have to figure out what mix of players works best for the team and get everyone on the roster to accept their roles. The first part gets talked about more, but the second is harder. Just about every player in the NBA has to sacrifice. Their best interests rarely coincide with those of the team. Players always want more minutes and touches. Their careers are short. They don’t have many opportunities to get paid. Basketball is chess, except the pieces have to agree to how they are being used.

Sacrificing is easier when a team is winning. Role players on good teams get paid. Role players on bad ones end up overseas. It doesn’t take long for losing to infect a locker room. Everyone starts pointing figures and looking out for themselves. For teams in the middle of the standings, the margin between the no. 6 seed and falling out of the playoff race entirely is razor thin. What looks good on paper may not translate to the court once the games start to count. A coach has to make the right adjustments or he risks losing the team.

With that in mind, here’s a look at five of the most interesting position battles in the NBA this season, and what they mean for their respective teams.

Dallas Mavericks: Dirk Nowitzki vs. Nerlens Noel at Center

Nerlens Noel would have been the perfect complement to Dirk Nowitzki five years ago. The Mavs spent most of Dirk’s career looking to pair him with a center. They solved the problem last season by turning him into one. Moving Dirk to the 5 stretches defenses past their breaking point, and keeping him in the paint on defense is the best way to save his 39-year-old legs. Dallas wants to keep him in the starting lineup, since sitting him for an extended period after warm-ups would cause him to stiffen up, which puts Noel in a difficult position.

The Mavs acquired Noel at the deadline last season to be their center of the future, but the two sides could not come to an agreement on a contract extension in the offseason. Noel will be an unrestricted free agent next summer. He won’t get the max contract he’s looking for if he’s playing 25 minutes a game off the bench. The good news for Noel is that Dirk is headed into his 20th season in the league. Even if he doesn’t get injured, he’s not playing 82 games. If Noel clicks with the starters, Rick Carlisle could have some tough decisions.

Noel gives the Mavs an entirely different look up front. He doesn’t have Dirk’s shooting ability, but he can be a devastating roll man and he’s a vastly superior defensive player. He can protect the rim, clean the defensive glass, and guard on the perimeter—all things an undersized Dallas team needs from their center. Carlisle will have to balance the past against the future. If Dirk retires at the end of the season and Noel walks, they could go from two centers to zero.

Charlotte Hornets: Dwight Howard vs. Cody Zeller at Center

The Hornets’ big acquisition this offseason was Dwight Howard. His best years in the NBA were with Steve Clifford in Orlando, and reuniting with his former assistant coach in Charlotte might be his last chance to be a featured player. Howard has played for four teams in the last six seasons, burning bridges on his way out of town each time. While he is only 31, there are a lot of miles on his body and the league has moved away from the style he’s most comfortable playing. The best centers no longer post up and wall off the paint on defense. They have to play on the perimeter on both sides of the ball.

Cody Zeller was the Hornets’ starting center when they made the playoffs two years ago, and they were 3-17 in games he missed last season. Zeller had the best on-court net rating of any rotation player (plus-5.4) and the second worst off-court rating on the roster (minus-3.6). No one else could fill his shoes as a small-ball 5. He sets good screens, rolls hard, and makes plays in four-on-three situations when the defense doubles Kemba Walker. On defense, he’s quick enough to guard the pick-and-roll and he knows how to position himself.

There may not be enough minutes to go around up front in Charlotte. Since neither Zeller nor Howard has 3-point shooting range, Clifford would have to install some high-low sets and go away from the spread pick-and-roll to use them together. Zeller’s biggest strength is his speed, which would be less of an advantage at the 4. If Howard gets benched, he may check out entirely. Both big men will have to sacrifice, and that’s even if the Hornets don’t play Frank Kaminsky at the 5.

Utah Jazz: Derrick Favors vs. Small Ball at Power Forward

The Jazz have tried to play Derrick Favors and Rudy Gobert together the last few seasons. They are two of the best defensive centers in the NBA, but finding a way to make it work on offense with both has been tricky, since neither is a 3-point shooter. Spacing the floor will be even harder with Ricky Rubio at point. Opposing defenses are going to pack the paint against Utah and dare it to beat them from the perimeter. Rodney Hood and Joe Ingles are good shooters, but neither will get many open looks given who they are playing with.

In last season’s playoffs, Utah went with a rotation of Boris Diaw and Joe Johnson at the 4. Diaw was big enough to play defense in the paint and skilled enough to play offense on the perimeter. However, he was also aging and out of shape, so they let him walk in the offseason. Johnson was a matchup nightmare for the Clippers, especially once Blake Griffin went down, but he’s a 36-year-old who needs to save his body over the course of the season. If Favors, Gobert, and Rubio don’t click, they need someone who can buy them minutes at 4.

The Jazz have several options. At 6-foot-10 and 230 pounds, Jonas Jerebko is mobile for his size, and he can knock down open 3s (career 35.2 percent shooter on 1.5 attempts per game). Ekpe Udoh was the Euroleague Final Four MVP. He’s a skilled and athletic big man, but he’s not a shooter. They could also go with a platoon of wings as small-ball 4s, giving Ingles, Johnson, and Thabo Sefolosha spot minutes at the position. Watch the battle for the final roster spot between Royce O’Neale, another European player, and Joel Bolomboy, a second-round pick in 2016. O’Neale is a wing, and Bolomboy is a big. Which one makes the team could indicate how Quin Snyder wants to play.

Denver Nuggets: Jamal Murray vs. Emmanuel Mudiay at Point Guard

The Nuggets don’t need much from their point guards. Nikola Jokic and Paul Millsap will handle most of the playmaking from the frontcourt. Wilson Chandler and Gary Harris will get the toughest defensive assignments on the perimeter. If Jamal Murray or Emmanuel Mudiay, both former no. 7 overall picks, can win control of the position, Denver could be a dark horse out West. Murray is 20 and Mudiay is 21, so a big step forward from either wouldn’t be a huge surprise.

They each bring something different to the table on offense. Murray is the better scorer, with per-36-minute averages of 16.6 points per game as a rookie. Mudiay is the more natural playmaker, and he’s better at making plays out of the pick-and-roll. Murray has the inside track on the job. His ability to come off screens and shoot 3s makes him a better fit with Jokic. Mudiay, on the other hand, is a career 36.7 percent shooter from the field and 31.7 percent from 3.

Defense may end up being the determining factor. Improving on that side of the ball will be huge for the Nuggets, who had the no. 29 defensive rating in the league last season. Jokic isn’t particularly quick, so they need their 1s to fight over screens and allow him to drop back in the paint. If Mike Malone can’t trust Mudiay and Murray with that responsibility, he could go with veteran Jameer Nelson or second-round pick Monte Morris. If he wants to get creative, he could use Jokic as a point center and play a three-wing backcourt with Harris at the 1.

New Orleans Pelicans: Everyone Capable of Spending Time at Small Forward

The only sure things in New Orleans are Anthony Davis, DeMarcus Cousins, and Jrue Holiday. Outside the big three though, the Pelicans rotation is as unsettled as any team’s in the league. It wasn’t particularly deep even before its annual rash of injuries. Now, with Rajon Rondo out four to six weeks with a sports hernia injury, and Solomon Hill out at least four months with a torn hamstring, Alvin Gentry doesn’t have a lot of options on the perimeter. The biggest hole is at small forward, where he is choosing between converted big men and smaller guards.

Dante Cunningham, their current starter, is more of a small-ball 4 than a 3. He’s a nine-year veteran who is coming off career highs in 3-point makes (1.2 per game) and percentage (39.2). Any regression would make him unplayable with Cousins and Davis. Cunningham is also better defensively at his natural position. According to the tracking numbers at Synergy Sports, he was in the 55th percentile among NBA defenders when guarding the roll man in the pick-and-roll last season and in the fourth percentile when guarding the ball handler.

Gentry’s other option is to go small with some combination of Holiday, E’Twaun Moore, and Tony Allen at the 3, but all those guys are needed in the backcourt until Rondo returns. The Pelicans are counting on Darius Miller, a second-round pick in 2012 who spent three unremarkable seasons in New Orleans before heading overseas, to eat minutes at the position for the time being. Don’t be surprised if they bring in another wing cut by another team in the next few weeks.