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The Dallas defense is in trouble

A deep dive into the trouble on the defensive side of the ball

NBA: Portland Trail Blazers at Dallas Mavericks Jerome Miron-USA TODAY Sports

The Dallas Mavericks (13-15) are currently 10th in the Western Conference, only two games behind the sixth place San Antonio Spurs. They’ve won 5 out of their 7 last games and Luka Dončić is playing the best basketball of his young career. During the last two weeks, the Mavericks offense is almost where it was last season, at the top of the league (second in the league over the last five games).

Yet, the ‘glass half empty’ Mavericks fans are either panicking or very unhappy. Dallas is at the bottom of the league in defense, ranked 28th per Cleaning the Glass. The ‘glass half full’ fans will say that the team was hit hard by COVID-19 and that Kristaps Porzingis missed a big chunk of the season, that he needs to find the rhythm and things will get back on track. And that the starting five of Dončić, Josh Richardson, Dorian Finney-Smith, Maxi Kleber, and Porzingis played less than 100 minutes together.

These are all valid points, but there is one problem: the defense is trending in the wrong direction. Dallas ranked fourth on defense on January 15th, 22nd on February 1st, and regressed to the current 28th place in February and is ranked 29th over the last 14 days. Like most fans, I’m pulling my hair out of frustration trying to understand what the hell is going on. Looking at the box scores after each game on my phone leaves more questions than answers.

With all the data and stats one would think you can ask Siri ‘Hey Siri what’s wrong with the Mavericks’ defense’ and get an exact answer. But we are not there, the robots are not taking our jobs just yet. So, I’ll try to play Siri for you to see if we can find some clues and answer key questions about Maverick's disappointing defense.

Note: Yes, only an NBA data-nerd like me can think of questions for himself and answer them with NBA stats.

The talk of the pre-season was about defense, and Mavs defended well out of the gate. Was that a fluke?

The Mavericks were not shy about their preseason goals. The plan was to bring in more defense and toughness. That was the reason for Seth Curry - Josh Richardson swap. Dallas drafted young athletic wings like Josh Green and signed Wes Iwundu. Early on, it seemed that the plan was working. Dallas was the 4th best defense in the league on January 15th. Unfortunately, it might have been mostly luck. The key element of a good early Mavericks’ defense was the opponent's effective field goal percentage. To be even more exact it was the opponent's three-point shooting percentage.

Before January 15th, Dallas was first in the league on opponents' three-point field goal percentage at 31.5%. Post-January 15th Dallas is last in the league, Mavericks’ opponents make 41.3% of their three-point shots. A huge 10% difference! And it’s not that Dallas is allowing more open looks on their opponent's three-point shots all of a sudden. Pre-January 15th, Dallas allowed 20.7% wide-open (6+ feet open) threes and opponents made 33% on them (second worst in the league). Post-January 15th Dallas allows 19.9% of wide-open threes and opponents make 42.7% (5th best in the league). There is a similar pattern in open threes (4-6 feet open) data. In a strange season, Dallas might be part of one of the weirdest opponent shooting swings. The bad news is that the defense was not really that good at the beginning of the season. The good news is that the current opponent hot shooting will regress to the mean eventually. We hope.

Mavericks were not a great defensive team last season, but they were never this bad. What changed?

Last season Dallas was ranked 18th on defense, so they were never this bad. If we compare last season and this season's data there some key differences.

Foul rate on defense - Mavericks foul at an alarmingly high rate

Last season Dallas was third in the league in defensive free-throw rate, this season they are 25th. One explanation could be that Dallas played more conservative defensive schemes last year. Mavericks were dropping their bigs in the pick and roll last season, while this season they are trying different coverages (more on that later). Last season the guards Dončić, Hardaway Jr., and Brunson fouled at below average rate for the position, and their foul rate is almost identical to last season. The difference in defensive foul rate is with the front-court players. Porzingis, Dwight Powell, and Willie Cauley-Stein all foul at a much higher rate this season.

Foul rate on defense

Opponent Shots - no rim protection

The Dallas defense allows similar shots than it did last year. The only difference is that the Mavericks allow a bit fewer shots at the rim and more three-point shots.

Opponent’s shooting frequency

The big difference, however, is in opponent shooting accuracy. Last season Dallas was 11th in the league in opponent field goal percentage at the rim, this season Dallas is 29th.

Opponent’s shooting accuracy

Looking at individual defensive field goal percentage in the restricted area, we can see that it regressed across the board for all players.

Defensive field goal percentage per player

Similarly, the block rate regressed for all main rim protectors compared to the last season.

Block rate per player

Kristaps Porzingis seems to be the elephant in the room when we talk about the Mavericks’ pick and roll defense. Is it that bad?

This might be one of the biggest differences if we judge the defense based on the eye test. Dallas, and especially Porzingis are struggling hard to defend in pick and roll this season.

Per Synergy Dallas was 11th in the league in pick and roll ball handler defense last season, allowing 0.869 points per possession. This season Dallas is at the bottom of the league at 29th spot, allowing 0.971 points per possession. Yikes!

As our editor Kirk says, defense is interconnected, but this might be at the heart of it. Last season Dallas mostly played a conservative drop coverage with Porzingis in the paint. They tried the same approach when Porzingis came back from injury this season but got burned on several occasions. Utah attacked Porzingis in pick and roll at every opportunity. Chris Paul and the Suns did the same thing, they targeted Porzingis in the pick and roll.

Reduced efficiency of drop coverages is not an issue only Dallas is facing. It seems that the league has caught up at exposing the drop coverage, as we see more and more players being capable of snaking pick and rolls and making the mid-range shot. This looks like the next step in the evolution towards skill-ball, and immobile big men look like the odd men out.

Lately, Dallas adapted their coverages and have Porzinigs playing much higher in the pick and roll. In the last few games, we saw Porzinigis and other bigs show, hedge, or even trap the ball handler. The problem is that Porzingis's mobility is not best suited for this kind of defense because of his size and limited mobility.

Here you can see some Porzingis in different coverages against two elite guards, Damian Lillard and Steph Curry. When Porzingis is in a drop, it results in an open three-point look. If he shows or hedges, he is just not mobile enough to prevent the ballhandler go around him and attack the rim.

The other problem is that it seems the Mavericks are trying with some of the new coverages on the fly. They are not the only team trying to do that. Milwaukee is one of the teams that is replacing a conservative drop coverage, with more switching and they are facing some challenges as well.

It takes time to automate coverages and all players need to be on the same page. That’s hard to do with no practice time. One of the key responsibilities of a big men defender in the pick and roll is to talk and communicate with the on-ball defender. If you want to see a perfect example of that, watch Draymond Green talk and orchestrate the Warriors defense. Porzingis is not there yet and it seems he’s still trying to figure out what he’s supposed to do, let alone instruct his teammates.

Here are two clips that show that Porzingis is not ready yet for more aggressive pick and roll coverages. In the first clip, you can see miscommunication between Porzingis and Richardson, where Richardson was clearly expecting a screen on the other side. In the second one, Porzingis misreads the screen angle and gets lost in space.

Is it only Porzingis’s fault?

Foul rate, defensive field goal, and block rate data show that Porzingis is definitely not the only problem. A big issue for Maverick’s defense is that their three key big men are off to a slow start and are not in good physical condition. Porzingis looks slower and less explosive after the meniscus injury, Powell is recovering from his Achilles injury and Kleber is trying to get his legs back after his COVID-19 absence.

But all defensive data, currently show Porzingis as the key problem on defense. His 119.5 defensive rating is by far the worst on the team. On/off stats show that Dallas allows 9.8 points more per 100 possessions when Porzingis is on the floor.

On/Off stats

This season Porzingis has a career low-rate block rate, steal rate, and a career-high foul rate. His rebound rate regressed compared to last season. Porzingis wasn’t the best individual defender last season, but he was an elite help defender at the rim. His rim protection is a big part of what made him the unicorn. This season, the rim protection and help defense are just not at the same level. Watch him on this play, where Dallas put him on a non-shooter Derrick Jones Jr. in one of the key possessions of the game. Porzingis is ideally positioned to provide help defense, yet he never gets there to contest the shot.

It doesn’t help that the team’s other rim protector Maxi Kleber is struggling as well. Kleber’s block and steal rates are at career-low points as well, as he was one of the Mavericks affected the most by COVID-19.

What are the short and long-term implications?

In short-term the Mavericks are just trying to survive. The offense is picking up, so the Mavericks are winning by outscoring opponents. This is enough when their shots are falling and against lesser teams. But with a defense that ranks in the low 20s Dallas is a fringe playoff team, that can expect a quick first-round exit as a best-case scenario.

Carlisle benched Porzingis in some of the recent games and used Cauley-Stein or Powell as more mobile defenders in the pick and roll. On a good night, Cauley-Stein is definitely the most mobile big defender on the roster. Here you can see Cauley-Stein using his agility and speed to contest Lillard on several drives to the basket.

On/off data shows that Dallas is currently a much better defensive team with Cauley-Stein on the floor. Carlisle can use him in certain matchups, but can probably not afford to bench Porzingis for longer stretches. Cauley-Stein is also not a player who performs well in an extended starting role and on a consistent night-to-night basis.

Some of the communication issues on defense will get better as the current starting lineup plays more together, and all COVI-19 affected players get to 100% physically. The team’s best three defenders Kleber, Richardson, and Finney-Smith were all affected by COVID-19 and many players talked openly about how long it takes to fully recover.

As for Porzingis, short-term Dallas needs to do everything possible to help him recover some of the agility and explosiveness and get closer to last season level. Long-term, current problems and limitations on defense present a difficult challenge for Dallas. If this version of Porzingis is closer to what we’ll see in the future, then Dallas has a problem. It speaks volumes that teams like Portland and Golden State choose to attack Porzingis more than Dončić as the weakest link on defense. Dončić improved in certain areas on defense this season, but he is not an above-average defender yet.

With Dončić as the main piece of the puzzle, Dallas can not afford to have another star that they need to ‘scheme for’ on defense. NBA Playoff basketball is brutal in exposing weaknesses and Dallas needs Porzingis to be a positive defender again. Porzingis’s progress on defense will be the biggest storyline as the season will progress. It’s the storyline that will define the ceiling for this team as currently constructed.