Behind the scenes of scouting Luka Doncic at Celtics practice

BOSTON — Defending Luka Doncic takes a team effort. There is no singular solution to slowing down the Dallas Mavericks star. But in Game 1 of the NBA Finals, the Boston Celtics found something that worked.

Boston switched everything, guarding Doncic straight up and choosing to take away the passes he usually generates. Dereck Lively II and Daniel Gafford’s lob game was eliminated, and the Celtics took away corner threes as well. “They are a scrappy team defensively,” Gafford said at practice on Saturday.

The Celtics have been tirelessly prepping to guard Doncic’s unique style of play, and assistant coach DJ MacLeay’s scouting has been a focal point of their efforts.

“I’m sure it was a collective effort, but coach DJ MacCleay has been kind of leading that charge,” Sam Hauser revealed at practice on Saturday.

But MacLeay is doing more than just scouting.

In Dallas’ heliocentric offense, Doncic is the sun, and the rest of the team revolves around him. At Celtics practice, MacLeay and Svi Mykailiuk are the suns.

“He’s literally been Luka,” Xavier Tillman told CelticsBlog at practice. “He’s been Luka. Him and Svi [Mykhailiuk].”

Both have been essential in Boston’s practice routine, but Mykhailiuk has taken to the role of Doncic a bit more naturally.

“What? Svi,” Tillman said with a laugh when asked who has been the better Doncic. “Svi’s got game. Svi’s good. Svi’s really good.”

That said, MacLeay has perfected some of Doncic’s moves, too.

“He loves the bump. He [has] a good bump spin,” Tillman said of MacLeay. “You know how Luka is really good at rolling off defenders? D-Mac got that locked down.”

MacLeay has worked closely with Tillman and a number of other Celtics players this year, particularly the big men.

Before games, MacLeay, Tillman, and player development coach Jermaine Bucknor compete in one-on-one drills where the coaches attempt to score on Tillman. The trio’s competitiveness always shines through as they keep score. Tillman’s competitions with the coaches have been a part of his routine since he joined the Celtics ahead of the trade deadline.

“I feel like that’s something that I look forward to when I come into the gym, and I have my individual time on the court, is to get with those guys and do competitive stuff,” said Tillman. “Being a dad at home, there’s not a lot of time where you get to be competitive, so when I get to be competitive, I love it.”

MacLeay’s meticulous scouting of Doncic and the Mavs and subsequent acting gig in practice have been crucial to Boston’s defensive game plan in the NBA Finals.

“DJ’s been great for us,” said Al Horford. “Just very clear with his concepts [and] what he wants us to do. Just kind of creating how he wants us to execute things. And I feel like our group, we’ve obviously bought in, and we’re really locked in and trying to do it the best we can.”

Photo by Adam Glanzman/Getty Images

Doncic scored 30 points in Game 1, but he only dished out one assist and created just six potential assists. It’s the fewest assists Doncic has had in a game all season.

Mixed in with a few possessions of drop defense when Kristaps Porzingis was on the floor, the Celtics forced Doncic into playing one-on-one with very little room to set up his teammates.

“They did their job well,” said Mavs forward Derrick Jones Jr. “They protected the rim how they’re supposed to. They sat down on our bigs’ legs, so we couldn’t get our lobs off.”

Dallas’ lack of lobs was staggering. On their road to the Finals, they converted 57 alley-oops— fifteen more than the next four teams combined. They averaged over three per game, yet against the Celtics, they had none.

A huge part of Boston’s ability to prevent the Mavericks’ alley-oop offense was putting Tatum on Lively and Gafford. Having him in that spot allows the Celtics to switch when either of Dallas’ bigs set a screen for Doncic, preventing them from rolling to the rim.

But that plan also requires solid rebounding, and Tatum was a monster on the glass in Game 1, snagging 11 boards, including nine on the defensive end.

The MacLeay and Mykhailiuk-led Doncic prep takes up a big chunk of practice. “I feel like, it’s probably like, if it’s an hour, it’s probably like a good 20 minutes,” Tillman said of Celtics practice. “Probably a third of it’s the defense.”

But rebounding has also been a major focus.

“A big portion [of practice] actually is rebounding for us,” said Tillman. “Like, I think Joe is really prominent on not giving up second-chance points. Especially watching the playoffs, you’ll see teams with, like, not big leads, but decent leads, and they’ll give up an offensive rebound [and a] three, and the team will be right back in it.

“Like, ‘see, they could have got the board and killed the whole game, but instead, they gave it up.’ So, that’s what we work on a lot. Just different boxout drills and stuff like that.”

Photo by Brian Babineau/NBAE via Getty Images

The manner in which Boston guarded Doncic took more than individual defenders. He shot 4/6 against Jaylen Brown and 5/7 against Porzingis, but the Celtics’ collective defense limited his effectiveness.

Switch defense is only as strong as a team’s weakest defender. In Game 1, Doncic treated Horford as his primary dart board, targeting him whenever he got the chance. But his plan failed.

The Slovenian superstar shot an abysmal 1/8 against Horford. He also shot 0/2 against Payton Pritchard and 0/1 against Hauser. After Game 1, Jrue Holiday praised the latter two. “Even our white guys guard,” he said.

If the Celtics plan to utilize this same defensive style moving forward, everyone who touches the court needs to be performing at the same standard on that end.

“He’s probably our best defender, so hearing that is pretty empowering,” Hauser said of Holiday’s comment. “Really, all you’re trying to do is make it as hard as you can on a guy like [Luka]. He’s so good. He’s going to make some tough shots even if you do play really good defense.

“You have to know it’s going to happen and just have to have a next-play mentality in terms of that. We were really connected last game, and we have to continue to be that way.”

Doncic’s outbursts are inevitable. He led the Mavs on a 31-12 run to cut Boston’s once 29-point lead down to eight in the second and third quarters of on Thursday night. But the Celtics’ defense stopped him from playing the game on his terms and held Dallas to just 89 points in Game 1.

MacLeay and Mykhailiuk aren’t Doncic, but based on Boston’s successful Game 1 defensive performance, they’ve been doing something right in practice.