PORTLAND, Ore. — How to explain the Blazers' offense? A year ago, Portland boasted a high-scoring offensive attack that ranked 11th in the NBA. This season, the team ranks 27th and is scoring about six points less per game.

The Blazers traded away sharpshooter Allen Crabbe in the offseason. Other than that defection and the addition of rookies Zach Collins and Caleb Swanigan, there isn't much difference between this year's roster and last.

So, who is responsible for the Blazers' offensive downturn?

Evan Turner and Maurice Harkless deserve some blame. Both have been negative contributors on offense this season. But the primary offender, which may be a surprise to some considering the expectations coming into this season, is Jusuf Nurkic.

As much as Nurkic has boosted the Blazers' improved defense – the Blazers allow nearly two fewer points per 100 possessions when he is on the court – he has been a drag on Portland's offense. (Story continues below)


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High usage, low efficiency

Nurkic has the second-highest usage rate on the team at 28.7 percent, which means he uses nearly a third of the Blazers' possessions, either through a field-goal attempt, free-throw attempt or turnover.

The problem is Nurkic has been an inefficient offensive player this season, while siphoning away possessions from the Blazers' two best offensive players, Damian Lillard and CJ McCollum. Lillard's usage rate is down 1.1 percent and McCollum's is down 1.5 percent.

The Blazers' offense is 4.7 points worse per 100 possessions with Nurkic on the court. When he's on the court, their offensive rating is 103.8. When he's on the bench, it's 108.5. That kind of gap is the difference between being one of the worst offenses in the league (as the Blazers currently are) and one of the best.

The only rotation player on the Blazers whose on-off numbers on offense are worse is Turner. The Blazers are 6.4 points worse per 100 possessions on offense when he's on the court. But Turner's usage rate of 16.0, which ranks eighth on the team, is nowhere near as high as Nurkic's rate, so his negative value is not as pronounced.

Bad shooting

Nurkic's inefficiency stems primarily from his inability to make shots. His field-goal and free-throw percentages – 45.1 and 64.7 percent, respectively – are unacceptable for a high-usage center who does most of his work around the basket area. The fact that he turns the ball over at a high rate (2.8 per game) and doesn't stretch the floor by shooting 3-pointers also hurts. Nurkic is one of the least efficient starting centers in the NBA.

True shooting percentage and effective field-goal percentage are two advanced statistics that account for free throws and 3-pointers, in addition to two-point field goals. Among centers who have started at least 25 games this season, Nurkic ranks 29th in the NBA in effective field-goal percentage (45.1) and 28th in true shooting percentage (48.7).

Only three centers have higher usage rates than Nurkic in the league: DeMarcus Cousins, Joel Embiid and Kristaps Porzingis. But look at how they compare to the Blazers center in efficiency.

Player Usage TS% EFG%

Cousins 33.6 58.7 53.8

Embiid 33.2 58.1 51.1

Porzingis 33.2 54.8 49.2

Nurkic 28.7 48.7 45.1

Nurkic is using up possessions for the Blazers like he's an All-Star caliber center, but he's not playing like it, at least not on offense.

Effect on Portland's offense

The majority of Nurkic's offensive touches come as the roll man in the pick and roll (28 percent) and through post-ups (24 percent) and cuts (14 percent). In those three categories, Nurkic's inefficiency is evident. His points per possession ranks in the 28th percentile in the NBA in the pick and roll, the 17th percentile in cuts and the 13th percentile in post-ups.

That inefficiency is reflected in the Blazers' offense. They rank 13th in the NBA in percentage of pick-and-roll roll man possessions, but 29th in points per possession on those plays. They rank 11th in post-up frequency but 30th in scoring on those plays. And they rank fourth in the entire league in frequency of cuts, but only 29th in efficiency with that play.

The Blazers' offense excels in pick-and-roll plays that end with the ball handler (second in the NBA) and in plays off screens (sixth in the NBA). They are also effective in isolation (tied for 16th in the NBA). Last season, their offense was efficient, if infrequent, in transition, though that has not been the case this season. When Portland is running inefficient plays like post-ups and cuts through Nurkic, it comes at the expense of more efficient plays.

Last season may have been an anomaly

Before this season, Nurkic only had a usage rate close to this high once in his career. During his injury shortened 2015-16 season, he led the Nuggets in usage rate at 27.2 percent. That was also the worst season of his career in terms of effective field-goal percentage (41.7) and true shooting percentage (46.0).

Last season, during a 20-game stretch in Portland, Nurkic's usage rating was pretty high at 25.7 percent. But he was efficient, with a true shooting percentage of 54.5 percent and effective field-goal percentage of 50.8 percent. Both stats are well above his career averages. Nurkic has not been a very efficient player during his NBA tenure, with a career true-shooting percentage of 49.6 and effective field-goal percentage of 46.4. Those 20 games in Portland last season are starting to look more and more like an anomaly.

During the rest of his career with the Nuggets, Nurkic was not featured in the offense as much, with a usage rating of 22.6 last season before coming to Portland and 20.7 as a rookie in 2014.

Is there a solution?

If Nurkic is to remain a Blazer, the answer may be to stop featuring him in the offense so much. It might be time to establish his role on the team as a rebounder and defender. His defense has been great this season. It's already established the Blazers are better on defense when he's on the court. He also ranks third among starting centers in defensive real plus-minus and fourth in defensive rating.

Nurkic's rebounding, previously a strength, has suffered this season, perhaps as a byproduct of an increased focus on offense. His defensive rebounding percentage is the second-worst of his career and his offensive rebounding percentage is the worst of his career by a significant margin.

Prior to this season, Nurkic's offensive rebounding percentage was never lower than 11.8 percent. This season it stands at 7.7 percent. Because of that, his total rebounding percentage is 15.5 percent, the lowest mark of his career. He's never had a percentage lower than 17.7 percent prior to this season.

The Blazers center still has value to the Blazers. If he can accept a reduced role on offense and focus his efforts on being a dynamic defender and aggressive rebounder, he can still carve out a bright future in Portland.

Jared Cowley is a digital producer at KGW. You can reach him on Twitter here.