The Boston Celtics are recovering from an identity crisis. While the lack of offensive production from the bench played a huge role in the Celtics' woes, the real problem was on the other side of the ball: defense.

Since winning the NBA Championship in 2008, the Celtics have been known for being a defensive-minded team. Their foundation was built on strong defensive principles. The Celtics could be described as a cohesive defensive unit with a number of players who could score big. With that foundation, the team could survive an offensive lull and still hold its own.

However, in the beginning of the 2012-13 season, the Celtics seemed to have lost that defensive identity. Due to the overall lack of defense, the team was not able to hold its own during the frequent offensive lulls. Boston clearly struggled with bench production, but the defense was not there to pick up the slack.

Before Avery Bradley's return, the Celtics ranked 18th in the league by allowing 0.925 points per play, according to Basketball-Reference.com. A year ago, with the help of Bradley's late-season emergence, the Celtics were second in the league at 0.856 points per play.

Since Bradley's return, the Celtics have seen significant defensive improvements. The turnaround was almost immediate. In the first three games with Bradley, the Celtics lead the league in opponent points, opponent field goal percentage and forced turnovers.

Bradley's impact on defense was apparent during the Celtics recent six-game win streak. During a Jan. 4 bout against the Indiana Pacers and a decisive win against the New York Knicks on Jan. 7, Bradley led his team in their defensive resurgence. The video below highlights those defensive efforts.

However, Bradley can't do it alone. Maybe the biggest reason for his "savior" label is the confidence that he instills in his teammates. When they see the work Bradley puts into defense, they try to match his effort.

Courtney Lee is the team's second best on-the-ball defender. Lee struggled to grasp his role on the team early in the season, but he's finally producing positive results. He and Bradley are the Celtics one-two defensive punch. Following a win versus the Knicks, Bradley told CSNNE.com:

Defense wins games. We're starting to understand that. When we were out there, me and Courtney wanted to make it hard as possible on their guards. That's what we try to do. We try to take turns picking them up.

 

Of course, the dynamic duo and the rest of the team will have to be consistent. While the Celtics are doing a much better job of contesting shots and causing trouble for offenses, they dropped the ball in last night's loss to the New Orleans Hornets.

The Hornets won the battle in the paint 48-32, and subsequently won the game. Rookie big man Anthony Davis finished with 10 points and 10 rebounds. Although the Celtics started strong, they couldn't generate consistent offense, which goes hand-in-hand with defense.

Sustained defense leads to improved offense. Defensive stops help facilitate the offense going in the other direction.

Rajon Rondo thrives in this system. Not only does it pick up the pace, but it also feeds into Rondo's ability to find the open man in transition. Great defense creates favorable mismatches for Boston in transition, which leads to easy buckets.

In the video below, Paul Pierce comes up with a steal to give the Celtics an easy transition bucket and a foul.

When the Celtics are playing well defensively, everything else seems to fall into place. The offense cannot succeed without the defense, and that is apparent through the team's early season struggles. When Bradley returned, the Celtics defense—and offense—was revitalized.

If Boston can consistently make stops on the defensive end, they should continue to see significant improvements and more wins. The recent six-game win streak was a direct result of improved defense. Defense is the key to the Celtics' success.