Luka has to be better. That's it. If he gives effort on defense and stops wasting time whining to the refs when he's getting to the line 20 times a game, the defense will improve. This season is a wash and was a wash before the Kyrie deal.
Luka needs a better offseason to get his body right. He's carrying 15 pounds of bad weight, at least. The Mavs offensive efficiency is decent but they are nearly last in pace. That has to change and Luka needs to be in shape to lead that change.
The 2023-2024 team should bear little resemblance to the current roster. Basically keep Luka, Maxi, and Josh Green. They need to dump THJ and Bertans for younger 3 and D guys. Use Kyrie and Wood in sign and trade deals to bring in complementary stars who are not allergic to defense. Dejounte Murray or Mikal Bridges would be the model, though neither is likely to be available. Let all the other UFAs on the roster walk (I mean specifically do not under any circumstances re-sign Dwight Powell). Thybulle is going to be RFA from Portland that would be a decent pickup. Bringing back Seth Curry as a FA would be nice as well. Yuta Watanabe would be a good FA pickup for the right price. The Bulls might be sellers, so Caruso, Vucevic, and even Lonzo might be worth kicking the tires.
Maybe none of the above specific transactions occur, but the current team is constructed haphazardly and goes only as far as the superstar with the dad bod at age 23 can carry them. Good luck with that.