Winning basketball at HOME. Not so good on the road.
Also, more credit needs to be given to some of the other Mavs players, as Luka came into to a pretty decent situation with Harrison Barnes, DeAndre Jordan, Wes Matthews, and Dennis Smith Jr. That's 1 all-star, 1st team all defensive player, two above average starters and one of the top rookies from 2017. That lineup just won a game (w/o Dončić) over the the Clippers to knock them out of 2nd place.
As good as Luka has been so far, it could easily be argued that the biggest reason for the Mavs improvement is DeAndre Jordan. So let's not give Luka too much credit. As much as I like him, the Mavs turnaround has been much more than him.
BTW, if Dallas doesn't start winning on the road, they may not be playing winning basketball for long.