I know Kyrie is getting all of this attention like it's the "Luka and Kyrie show". But IMO the 2nd most important player on the Mavs is Lively
You saw when Lively did not play when he got the head/neck injury, the Mavs offense looked shaky and easier to defend. Celtics defense have to focus on that Luka-Lively pick and roll 2 man game. That is what makes their offense go 10x. Lively is elite at lobs and a decent playmaker, and has great hands to catch in traffic. Him on the floor makes Luka have more space to operate, and makes the opposing team make a decision on who to guard
What I would do is put Tatum and Brown to defend that pick and roll. That way they can switch and both can defend either Luka or Lively. They did the same thing with the Haliburton-Myles Turner pick and roll
Sidenote, Lively is what Celtics fans wished Timelord Rob Williams could have been