As we head into the home stretch of the season I think a lot can be learned by looking at our hated rivals to the south. The Spurs are being heralded by many as a legitimate contender in the west, while the Mavs are being given little more than lower seed odds. What is interesting is that both teams started out the season in similar fashion: The Mavs started out 2-7, while the Spurs started out 2-5, including a loss to Dallas. As the season has progressed we've seen one significant trend, however, that has led to the divergent opinions on each team's fortunes: The Spurs return to defensive dominance, while the Mavs have continued to be little more than mediocre on the defensive end.
Take a look at the graph after the jump, which outlines the game-by-game defensive efficiency of the Spurs and Mavs over the season. Defensive efficiency breaks down how many points a team gives up during each possession, which accounts not just for how well a team contests shots, but also how good they are at forcing turnovers and stopping offensive rebounds. No other stat is better at showing how a team is performing on defense. In the graph below, I use a seven game rolling average, which takes away some of the "noise" you see in exceptionally good and bad games and gives you a very good idea as to how the team is trending over time. This chart looks at points given up per 100 possessions and lower numbers are obviously better.
The first thing to notice is the part of the graph marked as "A." Despite their poor records, both the Spurs and the Mavs started out the season very strong defensively. In fact, the first twenty games or so for both teams have been their best defensively so far this season. For the Mavs, the team also out-performed the Spurs for a run of games (from about game 15 to 20). Since that point the Mavs have never really come close to the defense of the Spurs.
In fact, the defining moment heading into the middle part of the season for both teams is probably the long run marked as part "B." Both teams were generally consistent for about 17 games, but the difference is that the Spurs settled in with a top five defense, while the Mavs settled in with a defense significantly worse.
The real story is how each team entered the new year and faced a challenging stretch of the schedule. The Mavericks, who were consistently mediocre, watched as the wheels came off and their defense collapsed. The Spurs, who were consistently excellent, hit a similar bump but quickly turned it around and kicked their defense into gear. This is indicated by part "C" on the graph. As you can see, this nearly 20 game stretch has featured the worst defense from the Mavs all season, while it shows a Spurs defense that is settling back into its groove.
Within this stretch of games, the absolute nadir for the Mavs defensively came during a 9 game stretch of the season when they had no less than three games with a defensive efficiency over 131. This stretch started with the 128-100 loss to the Suns and ended with the 124-100 loss to the Celtics. To put such horrible defense in perspective, the Sacramento Kings have the absolute worst defense in the league, and their defensive efficiency is 114.4.
If we use this as a microcosm of how bad the Mavs defense can be, how can we account for it? There were no injuries of note. About the only excuse can be that this was a particularly grueling part of the season. Seven of the nine games were away, and the Phoenix game was the second game of a home/away back-to-back. But is that an excuse? About the same time the Mavs were watching their defense fall apart (again, see part C in the graph) the San Antonio Spurs were watching their defense come back into focus. Did the Spurs have an easier schedule? No, they were on a part of the season where 11 of 12 games were away and also featured two back-to-backs.
Frankly, there was simply no excuse for the horrible defense being played for an extended part of the season. The fact that six of those nine games were losses is all the more evidence of how damaging the lack of defensive focus of the Mavs can be. Moving forward, the real question is whether this is a Mavs team that can play defense at all. It certainly hasn't earned any benefit of the doubt.
About the only thing that gives Mavericks fans hope is that the Mavs defense has been steadily improving recently. From the low point of the Phoenix game, the Mavs have been steadily tightening up their defense. This is indicated by the red arrow on the graph. Remember, a lower number is better, so a big slope downward from left to right is a very good sign. That's exactly what we see.
Of course, we may need to temper our optimism-the same time that the Mavs have been improving on defense, the Spurs have been improving as well. As it stands now, the Mavs have the remote hope that their defense will close out the season within the top ten in the league and better than average. The Spurs are looking at something entirely different: Defensive dominance.
It remains to be seen if this is enough to move deep into the playoffs. The worst defensive team to win the championship over the past ten years has been Miami, and they ended the year with the ninth best defense in the league. With the Mavs defense currently sitting at 14th in the league, things don't look good.