Winning the margins: who drives the Boston Celtics’ possession edge?

Joe Mazzulla typically talks about his willingness to “dominate the margins and dominate the possessions.” However how?

The general public typically focuses on offensive rebounding when speaking concerning the possessions battle. But, there are three different levers to this battle: defensive rebounding, forcing turnovers, and taking good care of the ball. As a result of this possession battle appears to change into increasingly vital, why not take a look at who’s the perfect at it? Who has essentially the most affect on the possession battle on a basketball court docket?

This concept got here after studying Owen Phillips’ glorious piece on the “Turnover Economic system.” I wished to dig deeper. What if we checked out this query from a extra particular person perspective—and included each turnovers and rebounding?

Utilizing 2024–25 on/off information from Cleansing the Glass, I attempted to estimate how gamers affect the variety of possessions their groups achieve or lose—each on offense and protection—after they’re on the court docket.

To take action, we’d like key metrics:

OFF POSS ADD (offensive possessions added) = (ORB% × 0.533) – TOV%

This tries to estimate what number of additional possessions a participant creates on offense, by grabbing offensive rebounds and limiting turnovers. The 0.533 issue comes from this season’s common miss fee—so it scales offensive rebounds to precise additional shot alternatives.

DEF POSS ADD (defensive possessions added) = Pressured TOV% – (Opp ORB% × 0.533)

This estimates what number of additional defensive possessions a participant’s group positive aspects due to their capability to drive turnovers and safe the rebound after a missed shot.

TOT POSS ADD (complete possessions added) = OFF POSS ADD + DEF POSS ADD

That’s the sum of each, giving a tough concept of how a participant shifts the possession stability per 100 possessions performed.

The rationale we’re utilizing on/off information is to keep away from the bias of focusing solely on particular person efficiency and moderately take a look at the affect a participant has on group efficiency. An awesome instance of why particular person rebounding metrics are biased is Andre Drummond. Regardless of being seen as among the finest rebounders of all time, his groups had been typically higher at rebounding when he was off the court docket.

The possession battle is a collective effort, and that’s why on/off statistics give us a greater sense of particular person affect. But observe that on/off additionally has its personal biases—similar to who’s on the court docket with the participant or who his backup is. No metric is ideal, however let’s dive into the numbers and attempt to perceive who’s the perfect Celtic at including possessions on offense and protection.

A two manner road

Whereas some groups, just like the Houston Rockets, are attempting to win the possession battle from the soar until the top of the sport, the Celtics appear to have one other method. Trying on the information, the Celtics seem break up into two totally different groups.

Within the backside left, you’ll find all of the starters. The gamers in that a part of the chart are those much less more likely to have helped the group win the possession battle this season. On the opposite facet of the road that cuts the chart in two, you’ll find all of the gamers from the bench who performed greater than 300 minutes.

Watching the video games, there was a transparent feeling that with Luke Kornet and Payton Pritchard on the ground, the Celtics had been crashing the offensive glass much more. However this two-way method to the possession battle goes past that. On each offense and protection—via rebounding and turnovers—the Celtics had been extra intentional about profitable the possessions battle with the bench unit than with the beginning 5. Why?

Profitable the possession battle typically comes from groups who lack offensive firepower or taking pictures, just like the Houston Rockets. Due to this fact, it is smart that the Celtics’ bench confirmed extra willingness to battle and create extra possessions to compensate for the extra expert gamers resting. However the offensive construction of the beginning 5 additionally had an affect.

Certainly, essentially the most influential gamers within the possession battle are sometimes facilities. Their measurement impacts rebounding, and the bottom they’ll cowl influences the flexibility to generate turnovers. Due to this fact, with Kristaps Porzingis spending most of his time on offense past the three-point line, it is smart that the Celtics’ beginning 5 is much less more likely to generate additional offensive possessions. Nonetheless, what’s extra attention-grabbing—and will have foreshadowed the Celtics’ struggles in opposition to the Knicks—is the beginning 5 underperforming on protection by way of producing additional possessions in comparison with the bench.

It’s no secret that the Celtics misplaced in opposition to the Knicks partly resulting from their incapability to guard the glass and their struggles within the margins. Nonetheless, over the course of a full season, are the Celtics who assist win the possession battle additionally those who assist win video games? Effectively—sure and no.

Is profitable the possession sufficient?

For individuals who learn quite a lot of my 10 takeaways and tactical deep dives, it gained’t be breaking information that the Celtics had been at their finest with Kornet on the court docket. As we see on the chart beneath, the Celtics’ backup large man was on the ground when Joe Mazzulla’s group was profitable the margins—and the scoring differential.

Additionally, some gamers had been nonetheless extremely optimistic regardless of not performing notably nicely within the possession battle—similar to Derrick White or Jayson Tatum. There have been additionally gamers who helped the group dominate the possession battle however weren’t as impactful on internet ranking, like Pritchard or Neemias Queta. After which, there are three gamers who underperformed in each: Porzingis, Jrue Vacation, and Jaylen Brown. Over the course of the season, the Celtics had been extra more likely to win the possession battle and have a greater internet ranking when these three had been on the bench.

General, this exhibits that the Celtics had been in a position to play two types of basketball: the five-out spacing with the starters, and the gritty possession battle with the bench. And whenever you combine all of it, you find yourself with a terrific common season. This additionally demonstrates that profitable the possession battle is vital—however not all the time sufficient to win. Additionally, observe {that a} participant’s affect on the possession battle relies upon closely on context and function optimization. At present, Kornet is among the finest gamers at serving to his group win that battle. Earlier in his profession, in a unique context with totally different assignments, he was one of many least impactful gamers on that finish.

If you wish to learn extra concerning the possession battle throughout the NBA, be at liberty to take a look at my latest Twitter thread on the subject: