Are the Blazers’ Defensive Struggles Surprising?

More than anything, this year’s Portland Trail Blazers have been consistently inconsistent. From game to game, even quarter to quarter, the effort and execution has fluctuated wildly. The same could be said of last year’s team which went through multiple slumps and hot streaks on its way to a surprising season.

Last year’s squad ended on a high note and the team built a narrative around its late success. That narrative went something like this: Portland was up and down all year but underlying that variance was an upward trend. A lineup change late in the year unlocked the roster’s true potential. After a surprising playoff run, the team was prepared to pick up where it left off coming into training camp.

That wasn’t all spin—I, for one, bought into it. There were some good reasons to expect that narrative to be true. There was palpable growth last year and the starting lineup with small forward Moe Harkless had great numbers (and still does) over a decently large sample size.

However, it would be foolish to call those reasons conclusive. There was always the significant possibility that last year’s finish was just another hot streak rather than a new, sustainable foundation.

On top of that, the Trail Blazers lost their two best defenders this season. One they lost to injury and the other they lost to…whatever it is that has befallen Ed Davis. Seriously, like nine months ago this dude was a dark horse candidate for NBA Sixth Man of the Year, mostly for his defense and rebounding. This year he looks ground-bound, without his usual activity.

Speculating about the cause of Davis’ struggles is fraught with difficulty but his exit interview provides one potential explanation:

“I’m going to put on some weight so I can check more of the back-to-the-basket guys, the centers. An extra 15 pounds would definitely help me bangin’ with those guys down there.”

And true to his word, Davis came into training camp around 245, about 15 pounds heavier than last season. The problem is, that extra muscle hasn’t helped him bang down on the block. He’s actually a little bit worse defending post-ups while his overall defensive impact has dropped precipitously. Even with the extra weight, Davis hasn’t been able to out-muscle guys. But now he can’t out-quick them either. He gave up one advantage and failed to gain another.

It’s interesting to note the difference between offense and defense and their reliance on individual players. If the Blazers had lost their two best scorers, everyone would expect the offense to fall off a cliff. But defense is more nuanced and interconnected. That makes it harder to judge and isolate individual contributions. It also makes it harder to adjust expectations when critical defenders go down or have a bad season.

We know that Al-farouq Aminu’s injury and Ed Davis’ bad year hurt the Blazers’ defense, but the question is, how much? That’s important because it has implications for the roster’s construction and the coach’s strategy. If Portland expects Aminu and Davis to return to form and their struggles are responsible for the majority of the defensive slippage, then it would be premature to substantially change the roster or make scheme adjustments. If one or both of those things aren’t true, then more fundamental changes are in order.

To try and estimate the “how much” question, we can use ESPN’s Defensive Real Plus Minus (DRPM) statistic. DRPM isn’t perfect, but it’s one of the more refined defensive statistics available and it measures exactly what we want. DRPM estimates a player’s “on-court impact on team defensive performance, measured in points allowed per 100 defensive possessions.”

With that information, we can estimate what last year’s Defensive Rating (DRTG) would have been if Aminu had been injured and Davis had been just as ineffective. It will also tell us what DRTG we should have expected this year, assuming last year’s finish wasn’t sustainable and given the “loss” of their two best defensive players.

*Credit side note: I also used stats from basketball-reference.com and nbawowy.com to calculate the estimates.

I won’t go through all the math here, but I estimate the Blazers would have allowed 82 more points last year if Aminu had been injured at the same rate he has been this season. And Portland would have allowed 79 more points if Davis had played like he has this year. That additional 161 points allowed would have raised Portland’s DRTG from 108.0 to 110.0 and dropped them from No. 20 to No. 27 in the league.

When I pulled these numbers, the Blazers hadn’t played the Minnesota Timberwolves yet and their defense was dead-last at 113.5. We might have expected a drop to 110 given Aminu’s injury and Davis’ struggles, but the drop to 113.5 is surprising. According to this methodology, a little more than a third of the defensive slippage can be attributed to the “loss” of Portland’s two best defenders.

These things will (hopefully) correct themselves, as Aminu recovers and Davis slims back down. However, that leaves about two-thirds of the problem that will require more active fixes from the rest of the roster. Coach Terry Stotts is absolutely justified in making adjustments. It’s good to see him experimenting after several years of stubborn dedication to a conservative scheme.

This analysis should also temper expectations for the trade deadline. If Aminu were healthy the rest of the season and Portland acquired a big man similar to 2015-16 Ed Davis—say, someone like Nerlens Noel—then we’d expect the defense to improve a few points per 100 possessions. Noel is probably better than peak Davis but it’s interesting to note that Davis’ DRPM was actually better than Noel’s last year. If Portland does acquire Nerlens, don’t expect him to single-handedly revolutionize the defense overnight.

There will be no silver bullets nor short-term fixes to Portland’s problems. Any significant improvement will have to come from multiple sources. Scheme adjustments, player commitment, effort, and roster changes will all be needed to drag Portland’s defense anywhere near average. At this point, trades and strategy experiments need to be made with an eye toward next season as well as this one.

Blazer’s Edge Night 2017

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