CelticsBlog exit interview: Luke Kornet

Before the 2024/2025 season, the Celtics’ interior rotation was one of the biggest enigmas. With Kristaps Porzingis out, Al Horford was the only certainty to start the season. But who would rise and establish himself behind him as the designated backup center? There were three candidates:

Luke Kornet (15.3 minutes per game in 2023/24)
Xavier Tillman (12.8 minutes per game in 2023/24)
Neemias Queta (11.7 minutes per game in 2023/24)

And, a year later, it’s a clear-cut victory for Kornet in this three-man battle. Tillman was quickly out of the rotation and Queta was in and out, without being able to consistently give good minutes off the bench. While they both lacked impact this past season, Kornet has been one of the most valuable players on the Celtics roster — especially considering his contract. Kornet’s impact-to-dollars ratio might be the best in the NBA. And if you don’t believe me, let’s dive into his season analysis.

The Celtics were better with Kornet on the floor

It’s always hard to measure the collective impact of a role player off the bench because his offensive load and defensive usage aren’t big enough to give him full credit for the team’s performance. Yet, the numbers indicate that, despite a minor role on offense and only 18 minutes per game, the Celtics were at their best with Kornet on the floor.

Indeed, with Kornet on the court, the Celtics were outscoring their opponents by 15 points per 100 possessions — compared to only 6 points per 100 possessions without him. How? Well, let’s use the four factors to understand what changes when Luke Kornet is on the court.

The four factors are one approach to understanding how basketball teams win games. It was developed by Dean Oliver and focuses on shooting efficiency, turnovers, rebounding, and free throws. This applies to both offense and defense.

Kornet’s offensive impact

Offensively, the Celtics were scoring 124 points per 100 possessions with him on the court. Looking at the four factors, the big difference-maker brought by Kornet is offensive rebounding. With him on the floor, the Celtics were grabbing offensive boards on 33% of their misses — compared to only 25% when he was on the bench. That’s a lot more opportunities over the course of a game. On top of that, the Celtics were more efficient shooting-wise when he was on the floor. This could be due to shooting luck — but not only.

Throughout the season, Kornet showed he was more than just a tall guy who could grab offensive rebounds. The most impressive part was the connection he created with Jayson Tatum on the pick-and-roll (which should have been used a lot more against New York). Per Owen Phillips, Tatum and Kornet were one of the most efficient pick-and-roll scoring duos. Thanks to Kornet’s elite screening ability, size, and court vision, the Celtics were able to build a dynamic offense around that two-man action.

His passing was also an important component of his impressive season. With an 11% assist rate for an 11% usage rate on CleaningTheGlass.com, Kornet is one of the best passing bigs in the league. The passing from the pick-and-roll was impressive, but he was also used as an offensive hub and connector from beyond the three-point line — despite not taking any long shots.

With these abilities to help offensive creation, finish at the rim, and increase the number of shooting opportunities, Kornet helped the Celtics become a better offensive team. It makes me wonder why he only played 13 minutes per game during the first four games against the Knicks. Maybe it was because of his defense?

Kornet’s defensive impact

As we did with the offense, let’s look at Kornet’s impact on the four factors on the defensive end.

In all four factors, the Celtics were a better defensive team with Kornet on the floor. Opponent shooting efficiency was down, turnovers were up, they got to the line less, and grabbed fewer offensive rebounds. Kornet is actually one of the hidden reasons why the Celtics remained an elite defense when Porzingis was out or Horford was resting.

The undrafted center is becoming one of the best rim protectors in the league. With him on the floor, Celtics opponents were taking fewer shots at the rim — and their field goal percentage in the paint also dropped. Game 5 against the Knicks was a great example of how Kornet can be used as a safety, punishing teams that lack spacing and taking away easy layups and dunks.

Thanks to his defensive activity, Kornet also helped the Celtics generate more transition opportunities with his blocks and steals. Per CleaningTheGlass, he’s one of the best defensive playmakers — with a 2.7% block rate and a 1.2% steal rate. But Kornet wasn’t only great offensively and defensively; he also unlocked the Celtics’ ability to play with two centers. Thanks to him, Boston was able to adapt during the regular season with various lineup combinations.

Unlocking the double-big lineups

When Kornet played as the lone big man, the Celtics posted a +12 net rating during the regular season. And when he shared the floor with another big, that number jumped to +18 (!!!). Thanks to Kornet’s versatile skill set, he was able to remain impactful alongside Horford or Porzingis — giving the Celtics an alternative to their five-out offense.

On defense, Horford’s impact was significantly better with Kornet next to him, as the veteran has become more vulnerable against certain matchups with age — but Luke was there to cover. With Porzingis, Kornet also brought great flexibility on both sides of the floor and allowed KP to focus on what he does best: extending possessions and protecting the rim.

What now?

The Celtics have a lot of contracts to deal with, and Luke Kornet’s is one of them. The good news is that they have full Bird rights and can offer him anything up to the max. But will they? The answer will depend on numerous external factors — from the offers the Celtics receive for other players to the ones Kornet himself might listen to.

The romantic in me hopes Luke is looking for a way to stay — and his recent appearance at a WooSox game tells me he likes it here. However, the NBA is a business, and feelings might not be enough to keep him in Boston. Still, with Porzingis’ physical uncertainty and Horford’s decline, Luke Kornet is the Celtics’ best center. So if they want to remain competitive, they should hold on to him.