Threes, mismatches, and individual talent. On the surface, those are the pillars of the Boston Celtics’ elite offense. Having two guys, Jayson Tatum and Jaylen Brown, capable of bending defenses with their isolation talent provides Boston with a near-infinite number of options on offense. And that’s without even considering the isolation talents of Payton Pritchard, Kristaps Porzingis, and Derrick White.
Yet, almost every single play the Celtics run finds its footing through the fourth, underappreciated pillar in Boston—screening. Whether it’s a guard screen, Luke Kornet, Al Horford, or anyone else on the roster, the minutiae of each individual pick is essential to its success.
And the details that go into the process are astounding.
Screening is the foundation of the Celtics' offense
Tatum and Brown’s ability to create space on the floor with their isolation skills drives Boston’s offense forward. But the mismatches they attack are produced almost exclusively by screens.
White and Jrue Holiday screen to bring guards into the action. Kornet and Horford screen to force bigs up the floor. Either way, the Celtics’ best possessions stem from their ability to set the right screen.
“Screen reads are important, regardless of who we're playing against,” said Joe Mazzulla. “Have to know what the coverage is, who's there, and those guys are very diligent. The player development staff does a great job teaching that, and the guys are diligent and have an understanding of what type of screen is needed.
“Usually when you see a good possession, the right screen is set, and when you see a bad one, we usually don't set the right one.”
The Celtics work tirelessly on their screening, emphasizing different points in practice and preparing themselves to make the right in-game reads on the fly.
Kornet works closely with Amile Jefferson, but the entire coaching staff aids in the lessons. Player development coach Ross McMains, in particular, has been crucial to Boston’s screen plans, and he’s aided Kornet since their days in the G League with the Westchester Knicks.
“When it comes to working five-on-five Boston offense, a lot of times, [player development coach] Ross McMains is kind of stressing stuff with it, just in terms of the actions that we're trying to do and what exactly we're looking for,” Kornet told Hardwood Houdini.
“So, I feel like in terms of just kind of knowing what advantages we're trying, and therefore, what screens we want to be setting, they've driven a lot of that in. I worked with Ross on that when we were in Westchester my rookie year and stuff, so it's got quite a lot of time doing stuff like that.”
But there’s only so much that can be practiced outside of in-game scenarios. The Celtics can predict their opponents movement and coverages, but that only goes so far.
“At a certain point it's just recognition,” Kornet said. “It's like, 'Oh, we're playing this type of team, they usually try to maintain.' And so, you kind of know what types of screens are going to be set that game, until they adjust. And then it's just kind of that next filter thing.”
The New York Knicks provide a perfect example. Karl-Anthony Towns spends most of his time in drop coverage. So, when Kornet rises up the floor to set a screen for Tatum, he knows to set it at an angle where Tatum can step in and pull-up from three. Towns won’t be there to contest at a high enough pick-up point, so the screen creates an open three.
But in the Celtics’ February 8 game at Madison Square Garden, Tatum was on fire. He forced the Knicks to change their coverage. So, when Towns started pressuring the ball above the three-point line, Kornet recognized this, rolled quickly into the paint, and was able to find an open Derrick White on the wing.
*Visuals of all detailed plays/examples can be found in the embedded video.
Screens don’t end once the body-to-body contact comes to a close. Sometimes, there’s no contact at all. The screener has to decide whether to roll or pop, whether to slip the screen or hold contact for as long as possible, whether to re-screen or get out of the action.
And all of those small decisions are made with the goal to give the Celtics an offensive advantage.
“As the game goes on, it's kind of like, settled into a way to be where they decide if they're going to adjust or they're gonna keep trying to do that thing well,” Kornet said. “And so then you're figuring out what the next layer of playing against that is. It's kind of like, what that level of advantage to create.”
When the Los Angeles Lakers were in town during the Celtics’ recent homestand, they didn’t use a center. Jaxson Hayes was out, so the Lakers ran small-ball. That left LeBron James as their primary rim protector for stretches of the game.
Kornet went to set a screen for Tatum, but James sunk back into the paint. Dorian Finney-Smith went under the first screen, preventing a drive, so Kornet adjusted, re-screened, and forced Finney-Smith to go over, leaving Tatum space to attack James downhill in the paint. Tatum drew free throws on the drive.
“You kind of know what they're gonna be trying to do, therefore, what counters are kind of going to be available,” Kornet said of in-game reactions. “So, there's a part of that, and there's a part [where] you're adapting on the fly.”
But for as much studying goes into reading defenses and adjusting screens, Kornet and the rest of the Celtics’ bigs also focus intently on what Boston’s stars like best.
For Brown, it’s working against guards. “JB, a lot of times, it's like getting guys on a certain position on his body so he can kind of just physically hold them there,” said Kornet. For White and Pritchard, it’s more traditional. “Small, quicker guards like D-White or Payton kind more operate, kind of like, traditionally, pick-and-roll in certain ways,” he said.
Meanwhile, Tatum is extremely unique.
“JT, obviously, is his own thing,” Kornet said. “It's just kind of based on where the pickup points [are], based on what he's kind of seeing against them, and what the big is kind of looking like, and what they're switching and just kind of what advantage or disadvantage you can have.”
Tatum prefers to attack bigs like Towns, Evan Mobley, and Jalen Duren in space, giving him room to drive by them into the lane. From there, he can either attack the rim or find a shooter with a kick-out. And if the big prepares for the drive too intently, Tatum is more than happy to hit a step-back three or middy in their face. But it all stems from the screens.
“It also has a lot to do with the guys shooting ability and comfort was kind of shooting those pocket-type threes, or if they're wanting to more drive and iso, or if they want to just get the switch,” said Kornet.
Kornet has enjoyed a career year this season, and he’s set himself up for a potential payday this summer. His rim defense has been immaculate, and he’s been great at filling space on the offensive end, but screening may be his most effective tool.
“His screening, for sure,” Mazzulla said of Kornet’s improvement this season. “His ability to screen versus different coverages is really impactful. And I think his physicality. His in traffic rebounds [have] increased from this year to last year.
“He's made some timely rim decisions and, defensively, protecting the rim. So, his screening and his physicality on both ends has gotten better for us.”
During his time at Vanderbilt and through the early seasons of his career, Kornet was a three-point shooter. His floor-spacing helped him standout, particularly when he was with the Knicks.
But since rejoining the Celtics for his second stint with the organization, Kornet has traded in the three ball for timely screen reads.
Not only is this best for the optimal success of the team, but it allows Kornet to transfer the same skills he used to find open threes into quality shots for his teammates.
“How I got shots early in my career was just being able to manipulate screens,” Kornet said. “[It was] my way to create separation.
“So, now it's just kind of like extending that for myself as like slips and rollers, and that's where it comes to finding shooters or even just knowing the positioning of everything and trying to create that initial advantage there. It's kind of the same sort of ethos of what we're doing.”
Screening is far more than the simple bump that translates over the TV screen. Setting a screen at the wrong time or at the wrong angle or in the wrong place can drastically alter a possession for the worse.
But setting the right screens in the right places at the right times at the right angles is what makes Boston’s offense as incredible as it is.
“That's what Joe, I feel like, has kind of talked about, where it's, if you're not creating the maximal kind of gap in that little part, then that's where things are going to get harder, versus, even attacking the coverage, so to speak,” Kornet said.
The Celtics’ offense may be driven by mismatches and threes, but hidden in the trenches are Kornet, Horford, and the screens that make those plays possible.
