Dallas Mavericks' Achilles heel is clear, and something has to change quickly

It's without a question the Dallas Mavericks have one of the worst defenses in the league. The team dropped one spot this week, as they now have the 23rd-worst defensive rating. Dallas's position has them sitting with non-contending teams such as the San Antonio Spurs and Portland Trail Blazers.

One issue could be the Mavs' defensive rebounding issue. Dallas currently ranks 22nd with an average of 32.3 defensive boards per game. This means they are only 2.7 rebounds ahead of the Trail Blazers for the worst spot.

However, the issue could be much more than that. ESPN's Tim Legler joined First Take on Monday to discuss the Mavericks' stance on defense. In simple terms, he states that Dallas' defense is on a transcending spiral.

Dallas Mavericks' Achilles heel is clear, and something has to change quickly

"Here's the problem, I'm going to start calling them out. They don't play hard enough. Its that simple. They do no lay it on the line defensively they way you have to, to be considered a legitimate contender. "

- Tim Legler

Legler elaborated on how the team has all the offensive intangibles to be competitive, but in simple terms, they don't compete hard enough on the defensive side.

Yet, Legler might be on to something. Offensively, the Mavericks rank with some of the top contending teams. Dallas has the 7th best offensive rating. Not to mention, they also average 118.7 points per game, the sixth-best in the league. It also helps when you have the league's top offensive player in Luka Doncic. Doncic leads the NBA with 34.6 points per game.

Another helpful aspect is Kyrie Irving. The Mavs' second-best player is averaging 25.7 points per game, as he shoots the ball well. Irving is knocking down 42 percent of his 3-point attempts. This ties him with Kevin Durant for the 17th-best percentage in the league.

Along with Doncic and Irving, Daniel Gafford has been huge for the team offensively. Whenever Gafford plays in 20 minutes or more, he has scored above 10 points in every game while being in Dallas. For example, against the Indiana Pacers, Gafford poured in 16 points in 21 minutes.

The biggest thing to note is that he leads the league in field goal percentage, averaging 68.9. percent.

So, the problem is simple: the Mavs' defense is non-existent. Look at Sunday's game against the Philadelphia 76ers. Dallas shot 46.5 percent against Philly and 39 percent from long range. They also outrebounded the 76ers by three boards and converted more fast break points. Yet, the Mavs allowed the opposition to score 52 points inside the paint.

Dallas isn't making timely rotations and the effort from the entire unit just isn't there. As Legler said, Dallas doesn't compete hard enough on that end of the floor to be contenders right now.

Gafford knows what they must do to get to winning basketball. He believes it's a team effort the Mavs must work on if they hope to get out of the bottom.

Now, the team must follow his lead if they hope to get back to winning basketball. He was bringing more energy and effort than anyone in Dallas' game against the Indiana Pacers on Tuesday, and that could inspire his teammates to do the same.

Luka Doncic, Kyrie Irving, and Daniel Gafford will look to get back on track Thursday when the Mavs play host to the Miami Heat.