Three years later, the Mavericks now have a big Porzingis problem in the NBA Finals.
Dallas coach Jason Kidd said before the start of the series that he didn't think Porzingis received nearly enough praise for his ability as a shot blocker and someone who can alter opponents' shots.
The 7-footer did both in his rousing return to the court in Boston's 107-89 Game 1 victory, while also providing a scoring punch — 20 points in 21 minutes of action — that jumpstarted the blowout.
It was a full display of his skillset by Boston that was never fully used during Porzingis' time in Dallas.
"He plays his role," Kidd said. "I think that's one of the things that's underrated about KP. When you ask him to do something, he does it. He doesn't complain about his role. He goes out there and tries to help his team win."
What's more, he did it in his first game back after missing more than a month of action because of a strained right calf muscle.
"Even if I have time off, I can jump right back in and I feel the same way," Porzingis said. "I know how to do this. That's it, just having that confidence, going out there whatever, first round or Finals, just going out there with full confidence and giving what I have to the team."
Kidd got to work with Porzingis for only 34 games during the 2021-22 season before he was dealt at the trade deadline to the Wizards. It was an acknowledgement by the Mavs that his use in a system in which he was asked to split time between posting up and shooting 3-pointers didn't mesh with star Luka Doncic.
"We're judged if it works or doesn't work. That's just part of the business," Kidd said.
There's also the risk that trading away a player of Porzingis' caliber could eventually come back to bite.
In Game 1 it did, with Porzingis igniting an early 17-5 run to help Boston take a 17-point first quarter lead.
But it's what he did on the defensive end throughout the game that made just as much of an impact.
Two of Porzingis' three blocks were at the rim — one each on Derrick Jones Jr. and Josh Green. He also blocked a pullup jumper by Kyrie Irving.
Dallas' primary big men, Daniel Gafford and Dereck Lively, combined to go 4 for 4 from the field and scored 10 points. But they had no blocks and only eight rebounds.
"He looked pretty healthy to me," Gafford said of Porzingis. "We have to find a way to match his energy and physicality."
Porzingis' presence in the paint also kept Irving and Doncic quiet. The duo, who had devastated opponents this postseason in the pick-and-roll by garnering 78 dunks or layups off their passes, managed only one such play in Game 1.
"That's what he's been doing his whole career. He's a great player. He's been great for us. The reason why we are here is because of what he's done," Celtics coach Joe Mazzulla said of Porzingis. "What he did for us (in Game 1) was big and we need that for the rest of the series."
If Porzingis keeps this production up, combined with the Celtics' other weapons, it may be too formidable for Dallas to match.
But the Mavericks are vowing to try.
"We just have to be better. We know that," Kidd said. "Boston is a really good team, and so we've got to be better on Sunday.