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Creating a Statistical Baseline for the Trail Blazers’ Defense

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Portland impressed on the offensive end of the floor last season, but the defense lagged behind for the Trail Blazers. How can we statistically measure their results on that side of the ball?

Portland Trail Blazers v Cleveland Cavaliers Photo by Jason Miller/Getty Images

The Blazers have a lot of intriguing players and dynamics this season and fans and pundits alike will be looking for signs of improvement. Everyone is wondering if internal growth can make this team elite and will be tracking both individual players and the team at large to form their opinions.

To track anything, you need a starting point. Without a baseline, you can’t measure improvement. So let’s make sure we have a common set of statistics before the season gets underway to track how this team changes and improves going forward, starting with the defense.

Team Defense

Defensive Rating: 105.6 points allowed per 100 possessions (Rank: No. 21)

Of all the questions facing the team, this is certainly the most important. The Blazers have proven they can score with the best of them but the defense was far from elite last year. If Portland is going to become elite they’re going to have to surprise some people on defense.

Defensive rating is a great overall metric but we can break that down into the Four Factors to get more granular. The Four Factors are shooting, turnovers, rebounding, and free throws and they determine, to a large extent, whether a team will win or lose. Those factors are then measured with the following four statistics. I’ve included the Blazers’ rank from last year to serve as the baseline.

  • Effective Field Goal Percentage Allowed: 50.3 percent (Rank: No. 15)
  • Opp. Turnover Rate: 13.4 Turnovers Forced per 100 possessions (Rank: No. 25)
  • Defensive Rebounding Percentage: 76.2 percent (Rank: 13)
  • Opp. Free Throw Rate (Opp FTA/Opp FGA): 0.307 (Rank: No. 28)

This defensive profile won’t surprise anyone who’s watched Portland under the tenure of coach Terry Stotts. The team punts on turnovers in order to stay at home and force less efficient shots. This is a big part of how the Blazers lower their opponents’ shooting percentage that highlights how these various categories are interconnected. Attempting to improve one can often put more strain on another.

Take free throws for example. It’s possible that the Trail Blazers are fouling opponents whenever they are in position for a good shot. If that’s true, then fouling less would lead to an increase in the opponent’s shooting percentage. Instead of going to the foul line, the opponent would be allowed to take more high-percentage shots.

We see more evidence for this theory when we pare it down even more, looking at the distribution of the opponent’s shots across different areas. If Portland is fouling when opposing players get near the rim then we would expect shots from that area to be artificially depressed. Look at how highly the Blazers ranked in shots allowed in the Restricted Area:

Shot Distribution

Now, this is nowhere near definitive. There could be many other explanations for Portland’s elite ability to prevent shots near the rim. It’s simply important to highlight how hard it is to improve one area without slipping in another. Limiting fouls by allowing more layups would obviously be self-defeating.

This is the tension Portland faces because they do some things well. That shot distribution is close to ideal from an analytics perspective. In every single zone they’re in the top 10. They force lots of 2-pointers away from the rim and limit corner threes. Portland doesn’t want to lose that.

The problem is that they cover those critical areas at the expense of everything else. Look at the breakdown of the opponent’s shooting percentage by zone:

Effective Field Goal Percentage By Location

Portland does a great job of contesting the most dangerous areas but is basically dead last everywhere else. Can they put more pressure in the middle of the floor and at the top of the key without creating leaks in the corners? It won’t be enough to simply improve their bad numbers. They have to do so without letting their good attributes slip. That’s what we should see if the team is really improving. Their numbers in the midrange and above-the-break threes should improve with minimal slippage in the other areas.

Play Type

This analysis so far has focused on the final result. Where does the opponent’s shot ultimately come from and did it go in? It offers no insight into how the opposing team is generating those shots. To look at that, we need play type data.

There are many different play types that could be included but I decided to focus on four.

Again, this profile won’t surprise anyone who’s watched the Lillard-Stotts era. The team chooses to defend the pick-and-roll with just two men as much as possible. This allows the players involved to score more easily but limits spot-up shots. We see that in the data here. Look at how much more often opponents take shots out of the pick-and-roll rather than the perimeter.

But Portland is basically dead last defending ball handlers and struggles to contest spot-up shots when they happen.

The Blazers need to either defend the pick-and-roll more effectively without help or send help and recover to shooters in time to continue to limit spot-up shots. We should be looking for the opponent's efficiency to drop without changing the distribution between pick-and-roll and spot-ups.

Individual Defense

Whether they can pull that off will largely depend on the weakest defenders improving. Meyers Leonard, Damian Lillard, and CJ McCollum form a trio of offensive dynamos who really struggle in a number of defensive areas.

Individual defensive statistics involve fewer interdependencies and tradeoffs. As a result, they warrant less discussion and I’ll simply present the numbers below. For Lillard and McCollum, defending the pick-and-roll, spot-up shooters, and guards coming off of screens will be most important. I also included Defensive Real Plus Minus (courtesy of ESPN.com) as my favorite all-in-one defensive metric.

If even one of them can improve their pick-and-roll defense it will make it so much easier to hide the other. CJ has some decent metrics in other areas but he continues to struggle in the pick-and-roll. As a result, when the Blazers can’t cross match Moe Harkless or Al-farouq Aminu they have no one to guard the opposing team’s primary ball-handler.

Of course, Meyers Leonard has a different set of relevant metrics because he’s a big man but the pick-and-roll is still right at the top. I also include defensive rebounding and Defensive Real Plus Minus:

Leonard has improved greatly as a rebounder but the Lillard-Leonard defensive pairing in the pick-and-roll continues to be a dilemma. Stotts would love to put that duo on the offensive end of the floor but it’s tough to survive on defense. Teams can easily put Lillard and Leonard in a pick-and-roll knowing at least one of them will make a mistake. But hey, the Irving-Love combo eventually found a way to make it work so there’s hope.

Rim protection is the other main part of Leonard’s job and there’s room for improvement there as well. Nylon Calculus has their own rim protection statistics and I included my favorite three from their suite below.

Rim Protection Statistics

Contest percentage is the number of shots near the rim that Leonard contests. Opponent field goal percentage is how often those shots go in. Points Saved per 36 minutes puts those numbers together to estimate how many points Leonard prevents relative to average. All together, Leonard comes across as a slightly below average rim protector. That might be fine on a number of teams but it’s tough to put an average rim protector next to Lillard and McCollum. If that trio is going to become an elite defensive unit they’ll all have to improve in multiple areas.

That gives us a decent statistical picture of the Blazers’ defense as well as a snapshot of some of their more important players. At various points during the season, I’ll come back to these numbers and see how the team is improving or deviating from last year’s metrics. Offensive improvement is less critical given the team’s success on that end but I’ll go through this same exercise for the offense next week. Stay tuned.