Stephen A. Smith breaks down the grim reality LeBron James could face if Cleveland falls to Kyrie Irving and the Celtics in the East. (0:52)

BOSTON -- Fresh off a four-steal performance that left him atop the NBA's steals leaderboard last week, Boston Celtics guard Kyrie Irving was fielding questions on his early season pilferage when he expressed dismay over a failed heist.

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"I had one gamble tonight where I put my hand up [to take ownership of his miscue]," Irving said after a lopsided win over the Sacramento Kings. "That's just not a great example for our young guys, especially when we're getting the lead and extending it like that. Kind of got overzealous and tried to go after [the steal]. You just take out the risk -- the high-risk ones -- and you just stay solid and you'll get a few a night, just being in the right spot."

Back in Cleveland, this suggestion probably sounded more outrageous than anything Irving had ever offered about the shape of the Earth. Over his first six seasons in the NBA, Irving was labeled an uninterested defender who gambled too often. Now, less than one month on the job in Boston, he was worrying about how that sort of defense might look to impressionable minds?

For all his obvious offensive talents, maybe the most eye-catching part of Irving's early season performance in Boston is just how eager he has been on the other end for the Celtics' league-leading defense. It's not just the steals or Boston's defensive rating when Irving is on the court, it's his obvious effort and desire to contribute on that end of the floor.

In his six seasons in Cleveland, Irving held an average defensive rating of 106.9. Through 11 games with Boston, that number is down 11.4 points to 95.5, even lower than Boston's league-best rating of 95.9.

Make no mistake, Irving still struggles at times to defend the pick-and-roll, but he's out there trying and that effort isn't lost on even his most defense-minded teammates.

"I'm very happy for Kyrie. I think sometimes you get labeled things and it's frustrating because it's like, 'I'm not what they're saying that I am,' " said Celtics big man Al Horford, the team's defensive quarterback.

"I'm just glad that [Irving is] in the right situation for him. He gets to lead our team, and really the key is him always being in the right positions. One of the things that I'm looking at on film so far is that he's always in the right spots. And if he's not, he's making effort and hustle plays and things like that. Guys, we see that, and we really appreciate that. He's really taken the lead on that, and he's been great for us on the ball."

Kyrie's come to play on defense Kyrie Irving is putting up some of the best individual numbers of his career this season. Here's a look at his career defensive rating via NBA data, as well as his points allowed per possession via Synergy Sports data. Season Def. Rating Def. PPP Percentile 2017-18 95.5 0.886 49th 2016-17 109.1 0.989 17th 2015-16 104.7 0.898 38th 2014-15 104.5 0.879 43rd 2013-14 106.8 0.903 34th 2012-13 107.7 0.850 58th 2011-12 108.5 1.039 4th

Irving doesn't seem particularly interested in putting the spotlight on himself for his defensive efforts. Before a game in Oklahoma City last week, Irving was asked if it had been satisfying to show what he's capable of on the defensive end this season.

"You said satisfying?" asked Irving, still processing the question. Then he immediately steered the conversation to the team as a whole.

"It's a long season, man. Our effort on the defensive end is at an all-time high," Irving said before maybe Boston's most noteworthy win on its current nine-game winning streak.

"When we're able to do it over a four-quarter game, I feel like we put ourselves in a great position to win. Offensively, it's not going to be the best every single night, but [defense is] one of the things we preach and it's one of the things we have systematically in place."

Still, it's impossible not to notice Irving's individual effort level on defense. Was defense something that coach Brad Stevens stressed to him after being dealt to Boston in late August? A smile crawls across Irving's face before his response.

"I mean, they had a whole tape. They had a whole tape," said Irving, referencing his first video session with Stevens on Boston's basic philosophies. "And our principles are up on the board [in the locker room] and you just gotta be in the shape to do it. Once that demand is on you and the expectation is there, you just gotta fulfill it. It's as simple as that."

Backed by the league's top-ranked defense, the Celtics have reeled off nine straight wins after an 0-2 start. Winslow Townson-USA TODAY Sports

When the dust settled on Boston's unprecedented summer overhaul, the Celtics had quite clearly upgraded their offensive potential with the additions of Irving and Gordon Hayward. Having moved Avery Bradley and Jae Crowder in trades to bring in those new stars, it seemed fair to wonder if Boston's defense might regress.

The exact opposite has occurred. Boston's defensive rating of 95.9, if maintained, would be the best defensive efficiency in the NBA since the 2004-05 Spurs (95.8), according to ESPN Stats & Information.

The Celtics have improved their defensive rating by 9.6 points from last season and that's the best improvement in the NBA this season, just a bit ahead of the Los Angeles Lakers, who visit TD Garden on Wednesday night (ESPN, 8 p.m. ET)

Boston's defensive success is maybe even more remarkable considering the team is starting two youngsters in 19-year-old rookie Jayson Tatum and 21-year-old second-year swingman Jaylen Brown.

But what the Celtics lost in defensive skill they seem to have made up for in size and length. In going from a perimeter of Isaiah Thomas/Bradley/Crowder to Irving/Brown/Tatum, the Celtics gained more than a foot in height and nearly as much in wingspan.

Like Irving, Thomas was a willing defender last season but teams were often able to exploit his height. Thomas ranked dead last among the 79 points guards in ESPN's Defensive Real Plus/Minus metric and 467th out of 468 players overall. Irving wasn't all that much better (ranked 69th in point guards and 440th overall) but appears poised for a drastic jump in this year's rankings.

With more size and versatility, the Celtics can safely switch defensive assignments without fear of getting caught in mismatches. Boston's length has translated to more disruption on the court, too. Traps get tougher to escape, entry passes get more daunting.

Boston ranks eighth in the league in deflections per game (14.3), according to the NBA's hustle stats, and is also third in contested 2-point shots (44.2 per game) and fifth in contested shots overall (64.5 per game).

Opponents' 3-point percentages have plummeted against Boston, and the Celtics have been the best defense on shooters in the league this season, according to Second Spectrum data. The company has a metric called quantified shot making (qSM) that takes into account who the shooter is, the type of shot and the defensive pressure.

"I'm very happy for Kyrie. I think sometimes you get labeled things and it's frustrating because it's like, 'I'm not what they're saying that I am.'"

Boston is holding opponents to an average of 3.4 percent below their expected qSM, the league's best number, according to Second Spectrum.

"I think that everyone that steps on the floor is really making a conscious effort to be in the right places defensively, and to have an impact on the defensive end," Horford said. "That's our mindset as a group. And we're all doing it.

"For whatever reason, last year was different. But this year I just feel like our guys, we're in the positions that we need to be and we're just trying to do what Coach is telling us."

Being in the right spots and not allowing cracks in its defense has also aided Boston's rebounding percentages, something that was an eyesore in recent years. The Celtics rank fourth in the NBA in defensive rebound percentage and second in total rebound rate.

Second Spectrum analysis notes that Boston is fifth in the NBA in rebound percentage above expectation (RAP+) as the Celtics get to 5 percent more rebounds than an average team based on their positioning at the time of the shot.

Stevens might finally have the personnel to maximize his defensive schemes, even if few of the parts came with a stellar defensive reputation on their own.

The Celtics lost Avery Bradley and Jae Crowder this summer, but Marcus Smart and Jaylen Brown have picked up the slack on defense. AP Photo/Willie J. Allen Jr.

One year ago this week, after getting overwhelmed in consecutive games by the Nuggets and Wizards, the Celtics ranked dead last in the league in defensive rating. The team did manage to collect itself in the aftermath and clawed to 12th overall by the end of the season. It's a friendly reminder that early results don't always indicate how the season will play out.

Still, after losing Hayward to a gruesome ankle injury, the way Boston has responded defensively has been truly remarkable. Much of that success can be traced to Horford.

Horford is allowing 0.733 points per play this season (107 points on 146 plays defended), according to Synergy Sports data. That ranks him in the 87th percentile among all league players but, drill down to players with at least 100 plays defended, and Horford is seventh in the NBA in points allowed per play.

Opponents are shooting a mere 34.7 percent against Horford, per Synergy data, and that's particularly noteworthy considering that the bulk of his possessions defended have come against some of the league's top early season scorers like Giannis Antetokounmpo, LaMarcus Aldridge, Kristaps Porzingis and LeBron James.

Boston's defensive rating with Horford on the court is 93.2, second best on the team among regulars (trailing only Aron Baynes, who has often started next to Horford in Boston's frontcourt). The Celtics' defensive rating spikes to 101.2 when Horford is on the bench, a number that would place Boston seventh overall.

"[Horford has] always been an elite defender, in my opinion," said Thunder coach Billy Donovan, who coached Horford at the University of Florida. "He's played a lot of different positions. He probably at times in his career has been a power forward, he's been a center, he's been back and forth between those two positions. But he's always been a terrific, terrific defender."

The Orlando Magic, cold in the first half, came out hot in the third quarter and Stevens needed something to cool them down a bit. So after Orlando trimmed a double-digit lead to four, Stevens essentially sent in his checking line while deploying Marcus Smart and rookie Semi Ojeleye midway through the frame.

Smart is a bruiser who seeks contact like a linebacker. Already regarded as one of the league's most tenacious defenders, he has been Boston's most effective defender this season. Smart is allowing a mere 0.628 points per play in 78 possessions defended, per Synergy data. Among players with at least 75 possessions defended, Smart ranks fifth out of 171 total defenders (last on that list of 171: Crowder at 1.202 points per play; Bradley is 135th).

Celtics coach Brad Stevens has trusted second-round rookie Semi Ojeleye with a key defensive role this season. Dale Zanine-USA TODAY Sports

Ojeleye is a mountain of muscle plucked with the 37th overall pick in June's draft. Stevens has thrown Ojeleye to the wolves this season, deploying him against some of the league's most elite talent. His individual numbers have struggled because of it (Ojeleye is allowing a still-respectable 0.867 points per play, per Synergy) but he has earned the respect of his teammates with his willingness to take on a challenge like checking an MVP frontrunner like Antetokounmpo.

"That dude looks like a ["300"] character," said Smart, referencing the 2006 action film. "He's strong as an ox. And I think Giannis realized that on a couple of times where he tried to bang him and he didn't go anywhere. But, as a young guy who has to step up to the plate with all the injuries and things that have happened, [Ojeleye has] responded really well."

In Orlando that night, the Magic closed the third quarter by making just four of 12 shots with Smart and Ojeleye on the court. Boston quickly stretched its lead back to double figures and ran away with a lopsided win.

"That dude looks like a [300] character. He's strong as an ox."

Stevens has the luxury of a bench filled with willing defenders this season. Baynes provides a toughness that Boston didn't quite have in recent seasons and he has experienced enough to help Horford with directing teammates. In 209 minutes of floor time, Baynes has the best individual defensive rating in the league, among qualifiers, at 87.2.

When Boston was on the verge of slipping to 0-3 in the first week of the season, Stevens even deployed rookie second-round pick Jabari Bird, an emergency transfer from the G League, and his defense helped Boston to its first win of the season.

The Celtics' defense got a boost last week with the return of Marcus Morris, whose size and versatility will fit right in and allow him to play a Hayward-like role with the first unit.

Stevens has built the system and set the ground rules. His guys have bought in. And the Celtics might finally have found the right mix to make it all work, even as a group of rookies get indoctrinated into the system on the fly.

"There's a more of a sense of urgency, no question, with our group," Horford said. "But our young guys have been great at really just being willing to learn, to do whatever it takes, and to buy in. It's important that we develop these good habits, defensively."

Having someone like Irving buy in has made sure that the other 15 guys on Boston's roster have done the same. And it's why Boston finds itself with the NBA's best defense when the rest of the league least expected it.