Inside The Numbers Of The Boston Celtics’ Historic Offensive Start

With a 16-4 record, on pace for 66 wins and looking hungrier than last season, the Boston Celtics are giving everyone headaches. When opponents walk into TD Garden, they know it’s gearing up to be a long night chasing around shooters, keeping two athletic forwards in front, and dealing with a defensive menace in Marcus Smart.

The Celtics dealt with a summer of hell. From the heartbreak of losing three straight games in the NBA Finals to the drama surrounding a coaching change, it would’ve been understandable if Boston looked disinterested to begin this season.

That’s before factoring in the rehab of Robert Williams III, who was expected to be out for two months after undergoing surgery on his left knee. Williams was the anchor of the best defensive team in basketball last season, helping spark their midseason turnaround that lifted them to the No. 2 seed.

With assistant Joe Mazzulla taking over as head coach and Malcolm Brogdon coming in to bolster the bench, they had to tweak a few things. Boston had to become a more offensively-driven team as they wait for Williams to return.

After the Finals, they knew it was imperative to develop stronger offensive habits so they wouldn’t collapse again on the biggest stage. To close out the Finals, they scored just 97.9 points per 100 possessions over the last three games, which would rank dead last in the league during the season. It was, in part, due to how often they turned it over – 20% of their possessions resulted in a giveaway.

Almost a quarter of the way into 2022-23, the Celtics have silenced everyone who predicted a step back in regular season production. Along with the best record in the league, they have performed at the highest offensive level we’ve ever seen.

In non-garbage time minutes, Boston has a 120.3 offensive rating, which is 3.1 points per 100 possessions higher than second place (Utah). That gap is equivalent to the margin between second and 11th (Dallas).

Offensively, the Celtics are connected in a way this group hasn’t shown before. Every action is purposeful. Every player is connected, moving on a string and working together to yield the best possible shot.

When Mazzulla stepped in, his emphasis was on decision-making and helping everyone feel involved. Up to this point, that’s what we’re seeing. The Celtics have been more intentional with their process, weeding out the bad possessions and terrorizing the opponent with their versatility – nearly every guy in the rotation can put the ball on the floor and make plays for others.

Boston is leading the league in true shooting percentage (62.0%), sitting 4.6 percentage points above the median (57.5%). Currently shooting over 40% from three-point range as a team, they have snipers spacing the floor so Jayson Tatum and Jaylen Brown can attack their matchups and force tough decisions from weakside defenders.

Either step over to show help, or try stopping two of the best wings on Earth without fouling. It’s much easier said than done. When one of them get a step and the low-man has to rotate, it allows Boston’s collection of role players – Brogdon, Derrick White, Grant Williams, and Al Horford – plenty of space to let it fly without a contest.

White, in particular, is in the midst of a ridiculous shooting stretch compared to his normal rate. After shooting just 28-of-91 on catch-and-shoot threes last year with Boston (30.8%), White has started 26-of-60 on those spot-up looks (43.3%).

For a guy the Celtics expected to just be a defensive stopper when they acquired him last year, White is totally changing the complexion of their team. With the trio of White-Tatum-Horford on the floor, the Celtics have a +15.9 net rating. We’re seeing the benefit of Tatum having high-quality shooters, passers, and screeners around him to make life easier.

Strictly in the halfcourt, Boston is scoring 107.8 points per 100 possessions. League-average is currently 95.7, giving the defending East champs a +12.1 relative rating. According to the Cleaning the Glass database, it would be the highest mark of the last 20 years. The data goes back to the 2003-04 season, with the 2012-13 Miami Heat posting the highest relative halfcourt offense (+10.9) since it was tracked.

Below is a list of every relative rating above 6.0 during that span, with the Warriors and Suns having multiple appearances:

The driving force behind Boston’s elite offense is how many spot-up threes they generate from touching the paint and playing inside-out basketball. So far, 72.8% of their total three-point attempts have come from catch-and-shoot opportunities. That’s slightly up from last season (70.3%). They are shooting 41.0% on those looks, the second-highest percentage in the league.

Aside from, well, making shots, it’s also paramount they take care of the ball. The Celtics are leading the NBA in turnover rate, only coughing it up on 12.9% of their possessions. It goes to show how effective a team can be when they value possessions and play with more intentionality versus driving into traffic without a plan.

Along with halfcourt execution, they have also made a leap in transition scoring. Boston is presently tied for 11th in points per 100 transition chances (127.5). Last year, they were in the bottom third of the league, ranking 26th with a 120.9 transition offensive rating (5.1 below average).

This Celtics unit will never be confused with the younger teams that love to push the tempo after every miss. Only about 15% of their possessions begin in transition, which is roughly average. But it’s still a tick higher than last season, and incremental changes are all you’re looking for when it comes to a Finals team.

Compared to what we’re used to seeing, these guys are wasting no time. Even if it’s not fully transition and there are multiple defenders back, the Celtics are getting into their stuff early. They are looking to shift the defense, exploit cross-matches, and simply catch teams off guard.

Notice this play below, in semi-transition, as Marcus Smart pulls multiple defenders with him and Brown cuts down the lane to attract more eyes. With Horford trailing the play, the Kings are clearly unorganized and don’t know where to be. This unlocks the extra pass to the corner as two Kings stunt at Horford:

Every year, it takes roughly a month into the season to identify a team’s philosophical or gameplan changes. You need about 20 games of a sample size just to isolate the outliers, also accounting for nights the team’s leaders or star players are sidelined. After a month, patterns on both sides of the ball will be clear. Only then is it safe to make proclamations about their championship equity and whether or not a style of play is better than the previous year.

For the Celtics, who largely kept the same rotation aside from adding another downhill attacker in Malcolm Brogdon, the biggest difference from last regular season is their shot profile.

Although Ime Udoka put them in a better position last year and encouraged more ball movement, they still had a tendency to settle for difficult looks that would disrupt the offensive flow. Even during the Finals, when the margin for error is always razor thin, mid-range pull-ups and misguided shots in traffic still crept into the Celtics’ offense at the worst time.

So far, the noticeable difference is Boston seeking more three-pointers on a nightly basis. They have trimmed some fat in the form of short-range floaters and mid-range jumpers, taking only 24.1% of their shots in those areas. Last year, it was north of 30%.

Mazzulla has prioritized more motion, an increase in north-to-south possessions that put pressure on the rim (instead of stopping short for pull-ups), as well as drive-and-kick threes.

With 44.4% of their shots coming from beyond the arc and 31.6% coming at the rim, they have elevated their location effective field goal percentage, which measures a team’s shot profile by projecting what their eFG% would be if they shot an average mark from each location. Last year, they were 19th. A month into this season, they are eighth.

The fear of being this high in three-point attempt rate is what could ultimately happen in a playoff series. Most people believe it’s risky to put most of your eggs in that basket, considering all it takes is having two cold shooting nights in a series to have your season flipped upside down. In a best-of-seven, you can’t expect to be shooting the lights out every night against tighter defenses and more aggressive coverages.

However, there’s a counterargument for Boston. They have the tools to fight through cold shooting and combat any defensive scheme. They don’t necessarily live-and-die by the outside shot – certainly not to the extent of those Harden Rockets, the team that made this a talking point in 2018 when they shot 7-of-44 from downtown in a home Game 7.

They can annihilate you in multiple ways, inching closer to a scheme-proof system that is always thinking one step ahead.

Above all else, the theme of Boston’s season thus far should be making the extra pass. Despite the team making roughly the same number of passes per game as last year, this group just feels different.

They went from 14th in assist-to-pass ratio to 5th this season. Every pass has a clear purpose. Every read is happening a couple seconds faster. Guys are spotting up in the right places, relocating when they should, and cutting on time.

Boston’s spread pick-and-roll sets are focused on the drive-kick-swing mentality other teams are using a lot (namely the Clippers). They don’t live and die by that style, though, as they only run the 16th-most pick-and-rolls in the league. When they space the court and decide to use it, the result is usually a clean look for a good shooter.

Here, as soon as Horford catches the ball, he’s entering ball-screen action with Smart. When Horford rolls, the defense collapses to cut off anything in the paint. Smart has become a very good passer in these spots, whether it’s to the roller or weakside corner. This illustrates how unselfish the team has been – Brown gives up a potential driving opportunity to hit White for a rhythm three:

Mazzulla has implemented more Spain pick-and-roll actions, too, which include a shooting threat coming up to set a backscreen on the original screener’s defender. This will often lead to confusion for teams that don’t switch everything, giving Boston even more scoring options:

The Celtics are getting more creative offensively, which is easier to do when you have a lot of continuity from the previous season.

It also helps when you’re able to leverage a superstar’s scoring ability to generate quality shots for others, and that’s exactly what Boston is doing with Tatum.

I really enjoyed this set on Friday night, as Horford and White started with a basic handoff that appeared to be flowing into an off-ball screen for Tatum to shake loose. However, instead of Horford screening for Tatum to receive the ball … the Celtics reversed it, with Tatum ‘pinning in’ his own man for Horford to get open:

That was a brilliant use of Tatum as a decoy, something you typically don’t see in the first quarter. But he was able to effectively screen two guys and generate a clean three for Horford, who is shooting 48% from deep this year.

After 19 games, Tatum’s individual numbers are sensational on the surface. He’s up to 30.5 points, 7.9 rebounds, and 4.6 assists on 62.5% true shooting, which would be the highest of his six-year career.

Dig a little deeper, though, and you’ll notice where he’s specifically made the most improvement. In the past, mid-range pull-ups were too frequently Tatum’s go-to shot in the halfcourt. Over the last two years, he’s focused on putting his head down, taking an extra two dribbles after receiving a ball-screen, and getting all the way to the cup. Combined with more threes – mostly off the dribble – he’s modernized his approach and learned how effective it can be.

When Tatum touches the paint, the offense is humming. First and foremost, he’s become a more reliable finisher in those spots. Within eight feet of the basket, his efficiency has improved each of the last three seasons:

• 2017-18 (rookie): 54.8%
• 2018-19: 58.3%
• 2019-20: 53.6%
• 2020-21: 59.8%
• 2021-22: 61.4%
• 2022-23 (19 games): 65.3%

Granted, we’re dealing with a small sample, but I’d bet on him staying around this mark for the entire season. His footwork is constantly evolving and he’s finishing with either hand in a myriad of ways. As it stands, he’s in the 94th percentile among all forwards in restricted area efficiency (76%), per Cleaning the Glass. Before this season, his career-high ranking was in the 79th percentile.

The biggest advantage for Boston moving forward will be how often he invites contact at the rim. It was the number one knock on Tatum for his first three years. He rarely got to the line, crippling the team’s chances for easy scoring opportunities. Again, that played into the Celtics being a mid-range heavy team.

A more aggressive Tatum over the last month has meant a higher free throw rate. Although Boston has collectively jumped only two ranks (22nd last year to 20th right now) in free throw attempt rate, Tatum’s individual numbers are where they should be. He’s generating 8.7 trips to the line per 75 possessions, an increase from his 6.4 mark last year. He’s also in the 80th percentile among all forwards in shooting foul percentage, drawing fouls on 14.5% of his total shot attempts. Both of those are career-highs.

Tatum has learned he can penetrate the lane against virtually any defense. Despite the ‘too small’ taunts being overused at this point, guard defenders are indeed too small and weak to keep him out of the paint. He’ll either use his added strength to absorb bumps and knock those defenders off balance, or his shiftiness will create openings once he unleashes the wicked crossover to get downhill.

Both Tatum and Brown have been hunting rim opportunities and trying to collapse the defense at all cost:

One thing I’ve noticed a lot over the last month is Tatum’s willingness to make plays out of his drives. It’s wildly different than how Boston looked last November, when they struggled to find an identity and the co-stars were frustrating other teammates with their lack of passing.

Now, Tatum is catching the ball in the middle of the floor – after being a screener! – and attracting bodies around the rim before making excellent drop-off passes. Or, if he knows he’s faster off-the-dribble, he’ll blow by his defender and force the opposing big to commit. Regardless of the situation, he always has a plan:

Tatum being utilized as the screener in side pick-and-rolls is perhaps my favorite look in Boston’s offense. Sometimes, it’s all about keeping it simple. Below, as Horford brings it up and engages in this inverted pick-and-roll, the Kings aren’t sure if they want to switch. The slight hesitation is what allows Tatum to slip out and create a wider gap for Harrison Barnes to recover. Right as the ball touches his hands, he’s driving down the middle:

If Tatum didn’t have an angle at the rim, Marcus Smart had a wide-open corner three after the Kings rotated. More than any other year in the Tatum-Brown era, the Celtics are unlocking multiple options on each possession. There will still be times it gets bogged down and isolation tendencies take over – as we’ve seen for decades, the playoffs will require those skills. But to get through the regular season grind, everyone has to feel involved and valuable to what you’re doing. So far, Boston is putting on a spacing and passing clinic to ensure that’s not a problem.

When all of the pretty options fail, the two stars enter bailout mode. Brown is shooting 57.1% on mid-range pull-ups, a KD-like efficiency. Tatum is at 44.7% on those long twos, much higher than he was last year.

You just aren’t going to stop this team from getting what it wants. When Mazzulla draws up something out of timeouts and gets them reorganized, opponents have no answer. As of Nov. 26, Boston’s offensive rating on ATOs (after-timeout sets) is 18.1 points per 100 possessions better than the league-median on those plays, which is 92.5:

The Celtics are embracing all of the right values offensively. It has them on pace to break NBA records as they separate themselves from the pack.

One of the old sayings around the league is that defense wins championships. While it’s true – you indeed have to stop people from scoring to win 16 playoff games – we’re seeing a shift in what impacts winning at the highest level.

In this era, a fluid, versatile, and unpredictable offense will always find ways to take advantage. The Celtics will still be a defensive powerhouse once Williams is back in the lineup. But in the meantime, this evolution was necessary. Their scoring attack needed some tweaks, and we’re now seeing the benefit of a team buying into modern principles.