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We're nearly an entire month into the NBA season. Earlier in the year, players' struggles could easily be chalked up to just a poor stretch of games. However, at this point, things are becoming concerning for players still failing to put it together. While plenty of mid-to-late-round fliers have struggled, the focus should be on the big-name players failing to deliver. As a quick note, players who are disappointing purely due to injury are excluded from this list. It's all performance-based.

Luka Doncic, Mavericks

The preseason MVP favorite is returning late-third-round fantasy value. His numbers are down nearly across the board compared to last season. Most notably, he's averaging 24.9 points and 6.7 assists on 44/30/71 shooting compared to last season's 27.7 points and 8.6 assists on 48/35/73 shooting. His poor free-throw shooting is ultimately hurting him the most, and he's currently on a second straight year of decline in that category. There's no reason to panic, though. His percentages should normalize, which will up his points and bring increased fantasy value.

Damian Lillard, Trail Blazers

Lillard has looked more like himself over the past two games, but it hasn't yet made up for his awful start to the season. He's averaging just 19.3 points on 37/26/86 shooting splits. It seems like the point guard is either avoiding contact or having a hard time with the new foul rules, as he's taking just 3.2 free-throws per game – a dramatic step down from the 7.2 freebies he was averaging across the past five seasons. It's also possible he's still recovering from an abdominal injury he suffered over the summer while playing for Team USA. The good news for fantasy managers is that he's averaging a career-high 8.3 assists per game, and he's still launching up 19.2 shots. Once he finally starts knocking them down, his fantasy value will normalize.

Jayson Tatum, Celtics

Tatum had a huge bounce-back game Saturday against the Mavericks with Jaylen Brown out. Brown is expected to be sidelined for at least a week, so Tatum will continue to see increased responsibilities. Still, it hasn't been the usage that's been an issue for Tatum. He's been inefficient, shooting just 39.5 percent from the field, 32.1 percent from three and 75.5 percent from the free-throw line. He's also down a full assist per game. It's possible the assists don't recover since Al Horford and Dennis Schroder are doing their fair share of playmaking, but Tatum's shots will start falling eventually, and he's taking 22 of them per game. The standout issue with his efficiency at the moment is that he's shooting just 50 percent at the rim – in the seventh percentile for forwards – after making 68 percent at the rim last year.

Russell Westbrook, Lakers

Westbrook's 32.3 percent usage rate is his lowest since his second year in the NBA, which isn't unexpected while playing alongside LeBron James and Anthony Davis. But even the time LeBron has missed hasn't boosted Westbrook's stock past sixth-round value. The point guard – not known for his efficiency – has been even worse than usual in that respect. He's averaging 18.8 points per game on an awful 41/26/64 splits. He's also giving away 5.1 turnovers to his 8.5 assists. The performance is even worse when you consider he's getting to the rim as much as ever and cutting the inefficient long-two out of his shot diet. He's shooting 54 percent at the rim – on pace for the third-worst mark of his career – and he's getting to the free-throw line the least of his career (4.8 FTA). It's just a tough watch right now, and probably be impossible for him to reach neutral value on his ADP (15).

Nikola Vucevic, Bulls

Vucevic is getting a bit lost in the revamped Bulls' offense. He's taking his fewest shots (14.3) since 2017-18, and he's been woefully inefficient, with splits of 38/26/72. On a positive note, he's rebounding (11.0), passing (4.3) and playing defense (1.2 STL, 1.0 BLK) well. His shooting will improve, but even when it does, his volume isn't there compared to his years as the No. 1 option in Orlando. He's a good buy-low candidate, but adjust your expectations. He won't reach value on his ADP (19).

Michael Porter Jr, Nuggets

Porter was a bust before he injured his back on a wide-open layup attempt – there's no timetable on his return, and messaging from the team has been very vague. Before the injury, he averaged just 10.9 points on 36/22/56 shooting, 6.9 rebounds, 2.1 assists and 1.3 steals in 32.2 minutes. He was shooting both much less and much worse than was expected coming into the season. It's bizarre considering the massive gap in the Nuggets' offense left by the absence of Jamal Murray. As it stands, Porter is the favorite for Fantasy Bust of the Year. He was high on that list before the season started anyway considering how unproven he was combined with his genuinely concerning injury history. As an aside, I'm worried that the Nuggets attached a max contract with as much downside as Porter's to an MVP in Nikola Jokic. If the back issues continue to flare up – which, again, is absolutely the expectation given his history – it may end up as one of the worst contracts in the league.

De'Aaron Fox, Kings

Like most players on this list, Fox's shot is just not falling. He's averaging 18.6 points on just 39/20/68 shooting. While his passing (6.1 APG), rebounding (4.0) and defense (1.5 STL, 0.5 BLK) are fine, it's tough to recover from throwing up that many bricks. Poor jumpshooting has been holding Fox back for his whole career, and it's discouraging to see him get off to such a rough start. At this point, I don't think opposing teams respect him in the halfcourt, which only makes things tougher. He'll improve, but probably not enough to get value back on his ADP (25).