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Looking at the Mavericks defense through numbers

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A mid-season review of a roller-coaster defensive performance

Dallas Mavericks v Orlando Magic Photo by Alex Menendez/Getty Images

Three weeks ago I wrote about Mavericks’s problems on defense. At that time Dallas was 13-15 and ranked 28th in defense in the league.

Since then Dallas won five out of six games and is now eighth in the Western Conference with an 18-16 record. Per Cleaning the Glass, Dallas ranked first in the league on defense since Feb. 16 and now ranks 25th overall.

Is this sudden defensive turnaround a fluke? Is it another wild opponent’s shooting luck swing?

We saw a similar trend at the beginning of the season when Maverick’s ranked third on defense on Jan. 14, but was then the worst defense in the league for more than a month.

Dallas defense is a roller coaster this season

I was so fascinated by these swings on defense that I decided to do a deep-dive into the defensive ratings for each game this season. I used Cleaning the Glass defensive percentile rankings for each game this season. 100th percentile rank means the defense ranked among the top defensive performance of the season, while zero percentile means one of the worst performances.

You can see the swings in the highs and lows of Maverick’s defensive performances. Dallas had four games ranked in the top 95 percentile of the league (vs LAC, MIA, MEM, OKC) and four in the bottom 5 percentile (LAL, second HOU game, fist GSW game, NOP).

The other thing that jumped out from the initial look at the trend, is that it looks like the Mavericks’ defensive performance this season can be split into three parts.

Development of the four factors on defense throughout the season

To understand the context behind the three parts, I analyzed four key defensive metrics. One of the more popular ways to measure the defense is to look at the four factors. These are: eFG% (opponent effective field goal percentage), TOV% (turnover rate), ORB% (opponents offensive rebounding rate), and FT Rate (opponents free throw rate).

Dallas ranking only 25th on defense is a by-product of being below average in all four factors: the Mavericks currently rank 17th in eFG%, 20th in TOV%, 19th in ORB%, and 21st in FT Rate.

NOTE: All data on the charts represent Cleaning the Glass percentile rankings. A higher number means better defensive performance. For example, a 95 percent rank on the opponent's three-point shooting means the opponent shot very poorly that game, while a five percentile ranking means the opponent shot extremely well.

An opponent effective field goal (eFG% trend per game)

Opponent three-point shooting (3P% trend per game)

Opponent shooting at the rim (At the rim trend per game)

Opponent turnover rate (TOV% trend per game)

Opponent offensive rebounding (ORB% trend per game)

Opponent free-throw rate (FT Rate trend per game)

Observations - First ten games (Dec. 23 - Jan. 14)

Four factors observations:

  • Dallas was 6-4 and ranked third on defense on Jan. 14
  • Dallas ranked third in the league in opponent effective field goal percentage (eFG).
  • Great opponent eFG was mostly driven by Dallas ranking first in the league in opponent three-point shooting percentage.
  • Per NBA.com stats, 19.9 percent opponents three point shots were wide-open shots and they made 32.4 percent of them.
  • Dallas was last, 30th in the league at opponent field goal percentage at the rim, but didn’t allow a lot of shots at the rim (fourth in the league at 29.3 percent of opponent shots coming at the rim).
  • Dallas was good at forcing turnovers (ninth in the league) but fouled a lot (25th in free throw rate).

Defense and other lineup observations:

  • Kristaps Porzingis was out until the last game of this stretch in Charlotte.
  • Dallas started with Dwight Powell at center, and Dorian Finney-Smith at the power forward position the first six games then replaced them with Willie Cauley-Stein and Maxi Kleber, while Finney-Smith moved down a spot to small forward.
  • The first COVID-19 related absences started on game number eight against the Magic.
  • It seems that the biggest reason behind the good defense in the first 10 games was the opponent's three-point shooting luck.
  • The smaller starting lineup with Powell and Finney-Smith was very good on defense but terrible on offense. These lineups forced a lot of turnovers, fouled a lot, and rebounded poorly both on offense and defense.

Observations - Brutal stretch in the middle (Jan. 15 - Feb. 15)

Four factors observations:

  • Dallas was 7-11 during this stretch and ranked the last in the league on defense.
  • Dallas ranked 29th in the league in opponent effective field goal percentage (eFG).
  • Poor eFG was driven by Dallas ranking last (30th) in the league in opponent three-point shooting percentage, but the poor defense wasn’t just the result of bad opponent shooting luck. Dallas ranked poorly in all other defensive factors.
  • Per NBA.com stats 20.4 percent of opponents three point attempts were wide-open shots and they made 42.4 percent of them.
  • Dallas was 28th in the league at opponent field goal percentage at the rim which was marginally better than in the previous stretch. The problem was Dallas allowed much more shots at the rim. The frequency of opponent shots at the rim increased from 29.3 percent to 34.8 percent (22nd in the league).
  • The defense forced fewer turnovers (22nd in the league), but the foul rate didn’t decrease significantly (23rd in the league).

Defense and other lineup observations:

  • COVID-19 absences were in full swing at the beginning of this period. Dallas started Porzingis and Cauley-Stein together for the first five games of this stretch. Josh Richardson and Finney-Smith returned at game eight of this stretch. The current starting lineup (Luka Dončić, Richardson, Finney-Smith, Kleber, Porzingis) was introduced at game eleven of this stretch. It was the first time that lineup had played all season.
  • For most of this stretch, the overall defense was significantly worse than opponent eFG%, which means there were structural problems on defense.
  • Especially in the middle of this stretch, Dallas struggled to defend against the good pick and roll teams. Utah, Phoenix, Atlanta, Golden State, and Portland all exposed the Mavericks' poor pick and roll defense. Dallas was at the bottom of the league in pick and roll defense (29th), allowing 0.971 points per possession according to Synergy data.

Observations - Last six-game stretch after a lucky schedule break (Feb. 16 - March 3)

Four factor observations:

  • Dallas was 5-1 and ranked first on defense during this stretch.
  • Dallas ranked first in the league in opponent effective field goal percentage (eFG).
  • Great opponent eFG was driven by Dallas ranking second in the league in opponent three-point shooting percentage. However, Dallas significantly improved defense at the rim (first in the league in this period). The frequency of opponent shots at the rim decreased from 34.8 percent to 29.6 percent (eight in the league).
  • Per NBA.com stats, 18.8 percent of opponents three point shots were wide-open and they made 31.7 percent of them.
  • The defense was still not forcing turnovers (22nd in the league), but the foul rate improved significantly (third in the league).

Defense and other lineup observations:

  • Dallas had an eight-day break before this stretch of games because of game cancelations due to the extreme winter storms in Texas.
  • Dallas played some bad offensive teams during this stretch (Oklahoma City, Orlando, Memphis) and got a break against Brooklyn with both Kyrie Irving and Kevin Durant being out.
  • Porzinigis missed the first three games of this stretch due to back problems.
  • Coach Rick Carlisle tried different coverages in pick and roll. Carlisle had Kleber defend the opposing primary big threat and Finney-Smith defend the ball-handler. This allowed Dallas to switch in the pick and roll, and enable Porzingis to protect the rim as a help defender. Opponent shooting at the rim improved significantly in the last three games, but the sample size is still small.

Looking ahead — what we’ll be watching

The starting lineup of Dončić, Richardson, Finney-Smith, Kleber, and Porzingis is on fire on offense. This lineup currently scores 131.4 points per 100 possessions on the season, which makes them the best offensive lineup in the league among all lineups that played more than 200 possessions, according to NBA.com. Unfortunately, they are also terrible on defense, allowing 120.8 points per 100 possessions. This lineup is good at rebounding but ranks poorly in the other four factors on defense. The improvement on defense over the last six games is encouraging but the sample size is too small to say the Mavericks finally turned the corner.

The biggest concern so far is that the only recipe for a good defensive performance is if the opponent shoots poorly on three-pointers. If you look at the chart where both game defensive ranking (blue line) and opponent three point percentage ranking (red line) are displayed, in almost all instances the red line is above the blue line. In a three-point heavy league, shooting from beyond the arc is important, but good defensive teams can have good defensive performances even when opponents hit their shots. The Mavericks need some sort of defensive identity, so far they were not aggressive (low turnover rate), nor being good at more conservative defense (high foul rate and low rebounding rate). There is the issue of random variance with all these three point shots, however, which The Ringer looked at a couple of weeks ago.

The other issue is that it seems that the Mavericks have a tendency to be playing down to the level of their competition. The Mavericks’ defense ranks 11th against the top ten teams in point differential, but only 25th against the middle ten, and 26th against the bottom ten teams in the league.

This makes you think that a big part of the problems on defense is still related to effort and focus. We see great defensive possessions or even good quarters, but rarely good defense throughout the whole game. This approach can work when the offense is clicking like it is currently, but it doesn’t bode well for the playoffs.

The Mavericks got two much-needed breaks that allowed them to heal and recover during the last month. The key defender whose improvement will matter the most on this Mavericks team is Porzingis. The league is smaller and faster this season, and defending in space is more difficult than ever for big men defenders. The Kleber and Finney-Smith combo defending primary pick and roll options is a nice wrinkle. They can switch and Kleber got better at staying in front of the guards as the season progressed. But good teams, especially in the playoffs, will find ways to get Porzingis defending in space. Porzingis was more mobile and active at protecting the paint in the last two games. Porzingis contested 19 shots against the Magic and 18 against the Thunder. Hopefully, this is a good sign that Porzingis can return closer to the level he was on defense last season. We saw positive signs from the team’s other key defenders Kleber, Richardson, and Finney-Smith during the last stretch of six games, and the Mavericks had a lot of practice time to work on their defensive rotations.

The Mavericks will need to improve the defense in the second half of the season. If they want to come out of the first round of the playoffs, they can not be a bottom-five defense in the league anymore. With the full and healthy roster, there should be no more excuses for failing to live up to their own pre-season expectations.