The Mavericks may not have been known as a defense-first team during their 12-year playoff run, but they always managed to do enough on that side to supplement their high-powered offense.
This year, however, their lack of defensive intensity is the primary reason why that streak is over, as Dallas managed only a 41-41 record in 2012-13.
The Mavericks ranked 27th in the NBA in opponents points per-game, giving up over 101 per-contest. Only three teams ranked in the bottom third of the league in opponents points per-game made the NBA playoffs, and all three (the Denver Nuggets, Houston Rockets and Los Angeles Lakers) were ousted in the first round.
As you can see in the chart above, the teams who ranked in the top eight in the league in defense averaged over 50 wins per game, and the amount of average wins decreases from there as you move on to the lower-ranked teams.
While offense may be seen in the highlights, it is defense that wins games and advances you in the playoffs.
The Mavericks know too well about this, as they failed to come up with good defensive performances in too many big games during this season.
If the Mavericks are going to become a playoff team once again next year, their first priority must be to improve defensively and get back to the form they were in in 2010-11 when they won the NBA championship and finished 10th in the league in defense.
For starters, the Mavericks must get better at protecting the interior.
When Tyson Chandler led the Mavericks' defensive unit two seasons ago, he was a stable presence under the basket that played great help defense, rebounded strong and blocked shots.
Even when the Mavericks didn't have Chandler, they seemed to always have one big on their roster who emphasized their defense during their playoff run (e.g. Brendan Haywood, Desagana Diop, Erick Dampier).
This season, Dallas simply did not have that.
While Chris Kaman looked like a good signing at first, his struggles defensively stood out on the court. Kaman has never been a great defender or rebounder, and injuries and old age have decreased his ability on that end even more.
Plus, playing alongside Dirk Nowitzki, the two seven-footers are too similar and slow-footed to be an effective combination defensively.
Off the bench, Brandan Wright wasn't much better, and Elton Brand, while a solid defender, was simply too short to move over and play center.
Bernard James showed flashes of being that player, but he is much too raw to be relied upon to be the Mavericks' primary stopper inside.
Dallas has to go out in offeseason and acquire a big man (or two) that can step in and play the role of rim protector next season.
Obviously, Dwight Howard and Andrew Bynum are the first names that come to mind, but there are more realistic options out there like Paul Millsap, Greg Oden, Timofey Mozgov or Nikola Pekovic who could come in and play that role.
There are also big men available in the NBA draft that could end up in Dallas if the ping pong balls fall their way.
Alex Len is a great prospect out of Maryland that could end up being a great defensive big man; Rudy Gobert has a huge wing-span and great athletic ability and Lucas Nogueira is a fantastic young shot blocker.
The Mavericks would be smart to stock up on big men. They are pretty well set on the offensive end with Dirk Nowitzki, but they need someone who isn't afraid to do the dirty work down low.
Furthermore, Dallas also needs to look into helping their perimeter D.
Darren Collison, O.J. Mayo and Vince Carter are all capable offense players, but none of them are really top-notch defenders.
Far too often the Mavericks' backcourt was outmatched by their opponent's top scorers, and the team relied too heavily on aging Shawn Marion to stop this every night.
There are plenty of guards available who can come in and play a big role in Rick Carlisle's defense next season.
The primary targets should be Tony Allen and Andre Iguodala, who are two of best defensive players in the league and would instantly improve the team's biggest weakness.
Beyond them, the team can look in the draft for a young player with good defensive ability, or go after some second-tier free agents who are excellent defensive players such as Jarrett Jack, Devin Harris or Lance Stephenson.
Beyond just acquiring players, the Mavericks simply must change their philosophy on the defensive end moving forward.
Rick Carlisle has done a great job turning around the franchise defensively, but this season the team has gotten away from that strategy.
The Mavericks seemed to only care about scoring the basketball, and they just didn't show up on the defensive end in several games. While some of that certainly has to do with the personnel, it is also a question of the team's effort.
However many players return to Dallas next season that were on this year's squad, they have to challenge themselves to be better than they were on defense.
If they need evidence to see that the best defensive teams in the NBA win more games, of the remaining eight teams in the NBA playoffs, seven of them ranked in the top 11 in the league in opponents points per-game average.