Damn, from reaching the NBA Finals last year to not even getting into the playoffs this year. That was like almost on top and then falling again. But AD did score 40 pts, but still not enough to lift the team. Washington was even scoreless in his 27 mins. Memphis dominated both offensive and defensive rebounds, especially the offensive, 16 compared to 7 of Dallas. As well as the points in the paint. The Mavs really did mess up their own team. They need to rebuild it again together with the remaining years of AD, Kyrie, and Klay.
Yes, Davis once again performed very well, but didn't get proper support from his teammates.
As for the Mavs roster rebuild, it may be without Irving since his current guaranteed contract with the Mavs ends after this season. Although he still has a player option for next season, it seems to me he would rather be a free agent.
The problem wasn't just the Luka trade though, people has to know that. Dallas wasn't the same team, and also Kyrie was missing too, if they had Kyrie, they could have gone to playoffs, and beat Memphis too. While they would probably not be in the finals, how many teams goes to finals two years in a row? AD did alright, so they have a good base, and if Kyrie comes back, and they do a few good FA signings, then I would assume they could actually do better next season.
Miami put years between their finals, but they built a good culture, Dallas may do that too. Luka on the other hand was a mistake of course, just because they made one mistake, they aren't this bad, they did a mistake but also had a injured superstar.