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The backbone of the Cleveland Cavaliers' 11-game win streak isn't LeBron James, Kyrie Irving or Kevin Love. It's not the new trade additions, the schedule or even the snazzy gold alternate jerseys.

For the first time all season, the Cavs are playing defense.

Scoring was never going to be a problem for Cleveland, not with all the talent it had compiled through the draft, free agency and trades. Stopping the other team, however, was a totally different story.

In their first 39 games, the Cavs allowed 100.1 points per game. Over their last 11, they've reduced this total to just 95.5. That signifies a jump from 19th all the way up to ninth in the NBA.

Here's how Cleveland's defense has improved—and why it's built to last.

What the Numbers Tell Us

We know that the Cavaliers are allowing nearly five fewer points per game during their win streak, but how?

There are a few factors involved here.

We'll start with one of the all-telling defensive stats: opponent field-goal percentage.

It's kind of a big deal. Cleveland hangs a board in its locker room that is updated daily with every team's percentage. James has pointed it out in postgame interviews. For the first two-and-a-half months, the Cavs were at or near the bottom.

On Jan. 14, the Cavaliers were 29th in opponent field-goal percentage at 47.1, per NBA.com. Only the Minnesota Timberwolves, an NBA-worst 8-40 this season, were ranked lower.

This awful stat could be attributed to a number of factors. Cleveland had no one to protect the paint, allowing teams to score at will inside. Defensive effort was spotty, with guys failing to regularly close out on shooters.

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Following James' return from a two-week rest period, coupled with the additions of Timofey Mozgov, J.R. Smith and Iman Shumpert, it's as if new life was injected into the team.

During the last 11 games, the Cavs have shown an inspired effort on both sides. Mozgov is clogging the paint, with Shumpert and Smith contesting perimeter jumpers left and right.

The results? Cleveland cut its opponent field-goal percentage to just 41.8 percent, good for fifth in the NBA over that stretch (the Golden State Warriors lead the league at 42.1 percent this season).

The Cavs are doing a better job closing out on shooters, communication is improved and everyone seems comfortable in their respective roles. If only for a few weeks, the Cavaliers have proved they can be one of the NBA's best teams when it comes to forcing misses.

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Controlling the glass has also been key for Cleveland. During their first 39 games, the Cavaliers were actually being out-rebounded by opponents on the defensive end 30.6 to 30.2. Now with the 7'1", 250-pound Mozgov in the fold, the Cavaliers are winning the battle 33.9 to 28.9. Love, Mozgov and Tristan Thompson are all averaging 8.4 or more rebounds per game.

All three are dominating the boards in different ways. Mozgov uses his size to overpower guys. Love utilizes his tremendous positioning and Thompson always remains active around the rim.

When it comes to defensive rating, or the number of points a team gives up per 100 possessions, the Cavaliers were again near the bottom of the league.

Before the streak, the Cavs possessed a D-rating of 106.3, 26th overall, via NBA.com. Recently, they've trimmed this amount to 100.4, good for 11th.

No matter where one looks across the statistical board, the new-look Cavaliers are rapidly rising up it.

The New Guys

First and foremost, the Cavs had to upgrade their personnel to become a tougher team to score on. Free-agent signings like Mike Miller and James Jones provide outside shooting but can't lock anybody down. Dion Waiters, before he was traded, only defended in spurts.

While Mozgov and Shumpert were brought on primarily for their defense, Smith has been a pleasant surprise on that end of the court as well.

All three bring different elements to the defensive end and can guard all five positions between them.

"The Cavs were one of the NBA's worst defensive teams before the trades for Mozgov, Shumpert and Smith. Now, they are among the best. We'll see if it continues, but the change has been stunning," noted Terry Pluto of the Cleveland Plain Dealer.

Let's start with Smith, who's never been confused for a lockdown guard throughout his career. The level of focus he's shown on both ends has been remarkable. Very seldom does Smith get caught out of place on a rotation, and he seems to enjoy one-on-one matchups on the perimeter.

His 6'6" height and athleticism provide an ideal building block to guard both shooting guards and small forwards. He's holding opposing 2s to a PER of 13.1 while limiting 3s to an even stingier 11.8, via 82games.com. The Cavaliers allow 2.1 fewer points per 100 possessions with Smith in the game.

For as well as Smith has played, Shumpert has been even better.

Well-known for his ability to guard three different positions, Shumpert has continued his strong defensive play in Cleveland.

As the 6'5" shooting guard recently told Chris Haynes of the Northeast Ohio Media Group:

I don't think anybody likes to play against me. I would hope nobody likes to play against me. I feel like if I'm going to go all out, there's no way you're going to like me at the end of the game. Until the clock hits zero, you're probably not going to be my friend. I would hope that that's everybody's mindset going into the game that until the clock hits zero, we're not friends.

Indeed, Shumpert has been a nightmare for opposing guards and forwards. How scary? His opponents are shooting just 17.4 percent on three-pointers since he came to the Cavs. That's a drop-off of 16.8 percent from their season average, via NBA.com.

While still recovering from a separated shoulder, Shumpert's minutes have slowly been on the rise. The more time he gets, the better Cleveland's defense will be. We could see him in the Cavaliers' starting lineup by the end of the season, taking major pressure off of James. The Cavs allow 8.3 fewer points per 100 possessions with Shumpert on the court, via 82games.com.

Even with Shumpert's strong play, Mozgov's impact has been even greater.

Mozgov leads the team with 1.6 blocks per game, which is nearly twice as many as the closest teammate (Thompson with 0.9).

His bulk is enough to make opponents think twice about driving the lane. Unlike a typical 7-footer, Mozgov moves extremely well for his size. He can step out to stop a point guard from driving and still recover in time to block a big man at the basket.

Before trading for Mozgov, the Cavaliers were awful inside. They began those first 39 games allowing opponents to shoot 62.7 percent from within five feet, 29th in the NBA.

With the 28-year-old Russian, that success rate has dropped to 56.2 percent, 11th in the league, via NBA.com.

Irving is extremely pleased with his new big man, telling Matthew Florjancic of WKYC:

He blocks shots. He's 7-2. Having that in the middle of the paint, it's tough for anybody going against us, guards and bigs. It's just a luxury we have as a team now. The type of defense we're playing with our bigs down the floor, they're also making guards take tough shots in there. They're making point guards get off the ball. It's a luxury that I'm taking advantage of. I can pressure the basketball and get into guys a little bit more.

Mozgov has made a huge difference inside and has even helped Cleveland change its style of defensive play.

Scheme Changes

Earlier in the season, the Cavaliers were routinely getting abused by the pick-and-roll.

Coach David Blatt tried to make up for the team's lack of a rim protector by "showing" a big man when the opponent would call for a screen. This means that either Anderson Varejao or Tristan Thompson, together with the point guard, would effectively double-team the opposing ball-handler.

This can work, in theory, but it requires a lot of switching from everyone else on the court so that no man is left open.

It wasn't pretty, but the Cavs had little choice. It was better than putting Varejao or Love in one-on-one situations at the rim, anyway.

With Mozgov, they no longer have to show.

Jim Mone/Associated Press

Dave McMenamin of ESPN.com provides further details:

Without giving away the farm, the change was explained by a person familiar with the Cavs’ defense as Cleveland now “downing” side pick-and-rolls (also known as “icing” or “bluing”) and forcing the ball handler toward the baseline, where there is a defender waiting and taking up that space. The Cavs used to “show” on side pick-and-rolls, asking the defender down low to come up to the point of the screen to try to disrupt the action with his presence before hastily retreating back to the lane. The new scheme doesn’t ask for as many constant rotations out of the Cavs, though it does allow the ball handler to get closer to the hoop, which presents its own challenges.

This means an easier job for the rest of the Cavaliers on defense, as they are almost daring opponents to try to score on Mozgov. This is something Cleveland would have never dared to do with Varejao as a starter.

This form of defense is simpler, conserves energy and lets Mozgov do what he does best.

The results speak for themselves.

Cleveland can absolutely keep up its tight defensive style of play, provided all the moving parts stay healthy. James and Shumpert are two elite wing defenders, Mozgov controls the paint and the new scheme allows everyone to become more comfortable with their roles.

The Cavaliers' defensive improvements are real, and they're spectacular.

Greg Swartz has covered the Cleveland Cavaliers for Bleacher Report since 2010.

All stats provided by Basketball-Reference.com unless otherwise noted.