The Celtics Have the Best Defense in the NBA Right Now

BOSTON — Marcus Smart and Robert Williams III missed the January meeting between the Celtics and Hornets, a 111-102 win for Charlotte where Terry Rozier and LaMelo Ball combined for 43 points and 20 assists. They set up threes for each other to close out the game late, Rozier burying six from deep over Boston.

Two weeks later, the Celtics stymied the fifth-ranked Hornets offense in the half court, struggling to contain the Charlotte fast break following Boston misses and turnovers, but never giving up the lead in the second half.

With Smart, Jaylen Brown, Jayson Tatum, Al Horford and Williams III intact, the Celtics have courted the best five-man defensive lineup in the NBA (min. 200 minutes), with a whopping 4.8 points fewer points per possession allowed than the second-place defense. Boston’s starters also rank fifth among qualifying offenses, scoring 116.4 points and allowing 90.6, the second best lineup in the NBA behind Minnesota’s starters.

Ime Udoka, defiant in starting a double big unit, switching everything and drilling defense first, said in January he believed that with stops, pace and shots falling, the Celtics could also climb into the top-10 offenses. They have, winning 10-of-14 after beating the top-seeded, albeit short-handed, Heat by 30 points and disrupting Charlotte’s offense two nights later.

Udoka has accomplished one of his largest goals in year one by turning around Boston’s defensive unit, fourth quarter slip-ups against the Hawks and Trail Blazers aside. During these past 14 games, the Celtics rank No. 1 in defense (101.8) by 5.2 points per 100 over the No. 2 Warriors since Jan. 8. That’s powered Boston to the No. 1 net rating in basketball over that stretch (+11.1).

“It’s always helpful when they’ve got guys like Smart and Rob Williams,” Rozier told CLNS Media post-game on Wednesday. “Them two was missing the last team we played them, and we made a big emphasis this morning that them two changed the game defensively. Rob being super long. Smart being a vet and knows what’s coming. He know all our plays and stuff like that. He making sure them guys stay intact and what’s going on. I think them two gets it started. Then you got a lot of guys that want to play defense, Schröder, I can keep going down the line, Josh Richardson.”

Pushing the pace

Botching the fast break became one of the staples of the Celtics’ offensive misfortunes earlier in the season. Boston ranks 26th in points per possession in transition (1.04), with a 50.2% (T-23rd) efficiency on those plays.

Charlotte and Miami tied for seventh in those situations, so the Celtics would need to overcome that disadvantage, winning the fast break battle 13-2 over the Heat and beating the Hornets in spite of a 24-10 loss in in transition.

Udoka talked last week about the connectivity between offense and defense. The Celtics have regressed in fourth quarters to a 111 defensive rating (22nd) due in part to the 24th-ranked offense they play in clutch situations.

It works in reverse, as they’ve started to turn their stops into quick entries into the offensive zone. Smart’s urgency on the ball both helped get into the offensive zone fast, and more importantly make quicker decisions.

The Celtics need to clean up their defensive rebounding game to initiate more of these opportunities, losing to a poor Hornets rebounding unit and allowing 14 Charlotte offensive rebounds. Overall, their starter’s 54.8 REB% tops qualifying NBA lineups thanks to Horford and Williams’ size. The duo combined for 20 of Boston’s 42 on Wednesday.

The Celtics rank 25th in pace, and their starter’s 98 pace stands outside what would be the top-10 mark among teams. That and spacing are two of the factors that make the Celtics’ double big unit unplayable outside of crunch time. Replacing Horford with Richardson, as Boston did Wednesday, bumps their pace above 99, which would fit just below the top-10.

“Partially flow of the game. Get a read on what we’re doing there and offense vs. defense,” Udoka said, explaining his crunch time defense over the weekend. “A lot of times, teams downsize at the end and we’ve obviously matched that at times defensively. If a unit is playing well, or individuals, we’ll go back to that as well. So it’s a little bit of both.”

The speed of their half court offense always matter more to Udoka than running the floor though. Boston’s average second per touch now tied for 13th in basketball, pointing in the right direction. The first half of the win over the Kings saw the Celtics set a season high for kick-ahead passes. 

Cutting off the paint 

When teams try to line the Celtics’ starters up, they’re facing Smart at the point of attack, switching onto Horford if they receive a screen. If they blow downhill past Horford, they’ll run into Williams III at the rim.

That triple-layered path to the basket usually leads ball-handlers to double back to the perimeter if they can even touch the paint.

 

Only the Heat and Warriors allow fewer shots at the rim than the Celtics, which remains the most valuable real estate in the NBA. Boston probably sacrifices some of its three-point defense (they’re roughly league average) to completely eliminate post touches through their pair of big men.

Throw in the length of Brown and Tatum, and the Celtics have no weak links among their starters. NBA offense is all about creating advantages, and it’s hard to find any against Boston’s large, active and long starting collective. Plus, they’re leaning into Williams III as a shot blocker.

Udoka found the sweet spot between Horford’s ability to defend in space, which remains unique among big men, and Williams III’s twitchy shot rejecting. Rob’s length deters shots at the rim even when he’s not sending them the other way, while Horford can comfortably play the pick-and-roll alongside Smart and defend the perimeter when he’s isolated on an island.

Horford has contested the 14th-most threes in the league this season and the 13th-most two-pointers. Williams III ranks 17th in contested twos and fourth with a 6.6 BLK%.

Horford, who’s blocking less shots in his perimeter role, can play drop defense with second units and reject enough attempts to match Giannis Antetokounpo’s 4.3 BLK%.

Williams, as he showed to end the win over Charlotte, isn’t too bad at guarding the perimeter himself.

“You’re going to beat me out for being one of the best defenders out here,” Smart told Williams after. “Keep going.”

Marcus Smart 

We talk about Smart’s defense so often that it can feel stale, cliché or overrated. But he’s actually that good. This play to save Brown from his turnover factor significantly into a close game’s outcome, and almost exactly mirror the chase down on Norman Powell that won the Celtics Game 7 over the Raptors in the Bubble.

The Celtics have won 5-of-6 since Smart returned from COVID injury, his 90.2 defensive rating over that stretch 4.2 points better than Tatum’s in second place on the team. When Smart’s on the floor this season, the Celtics allow 4.8 fewer points per possession (83rd percentile), reduce their opponent’s eFG% by 1.8 percentage points (78th percentile) and increase their turnover rate by 1.0 percentage points (72nd percentile).

His boxing out also significantly limits opponent’s offensive rebounding and his greatest value remains swinging the possession total throughout the flow of the game, which is less noticeable than the old school defend one guy all game and lock him down meter of ranking defense. All of this goes without mentioning the offensive boost he’s given the team. 

Smart fills all the cracks, orchestrates the defense and predicts passing lanes as well as any guard in the league. His 2.8 STL% is tied for fourth in the NBA. He also remains incredibly difficult to penetrate at the point of attack. Smart defends nearly 12 shots per game, holding opponents to a 44.3% FG, below the league average of 45.5%.

 

The bench 

Dennis Schröder (105.8), Grant Williams (107) and Josh Richardson (107.3) aren’t significant drop offs from the starting unit’s dominance. Schröder’s hands and effort on that end, even when his positioning wanes, renders him playable with the Celtics’ system.

Williams’ switchability is one of the pleasant surprises of this Celtics season. Although he’s the most likely of any of Boston’s regular players to get attacked, he’s improved his ability to slide his feet and remain upright. Foul issues plague him less than they do in the past and he stuck with Tyler Herro on Monday to record one of the most impressive stops of his career.

Williams also knows exactly where to be on the floor, Udoka noting he can defend smaller and larger players.

Richardson has also provided long on-ball defense, strong shot blocking for his size and the ability to prevent entry passes against larger players. Richardson and Williams played this game-breaking pass by Ball about as well as they could have on a night where Ball scored a career-high 38 points.

Schröder, Richardson, Grant, alongside Tatum and Horford post a 96.1 defensive rating. Brown and Horford with that bench trio drop to 113.3 in 37 minutes. The bench with Tatum and Williams III have a 129 defensive rating and sneaking Smart and Horford in alongside Tatum, Schröder and Richardson give up 125 points per 100 possessions.

The bench needs work that’ll come at the deadline, as the Celtics balance offense and defense, with Schröder almost inevitably gone and Richardson likely being the key matching salary in any deal. How the team handles Horford, considering his lagging offense and excellent defense as part of this dynamic could be a swing factor in how much Brad Stevens buys into the defensive identity that Udoka’s built.

The Suns and Bucks both finished top-10 in defense and top-10 in offense last season. The Lakers, 76ers, Jazz and Knicks lost before the conference finals, while the fifth-ranked Warriors fell in the play-in tournament. The Grizzlies, Clippers and Heat lost early in the postseason too, setting the table for growth we’ve seen from all three into the 2021-22 season.

That could be the benefit of the groundwork Udoka is building. The Celtics seem to embrace their defensive identity, Brown laying down the perfect contest on Ball’s three-pointer ahead by four points with 13 seconds remaining to ice the game. Then, with the win in hand, Smart and Brown stuck with Rozier and Ball until the clock expired. A contrast against the threes both Hornets heaved over their heads weeks ago.