The NBA is investigating the facts and circumstances surrounding the Dallas Mavericks' roster decisions and game conduct after their loss to the Chicago Bulls, according to league spokesman Mike Bass. The Mavericks entered Friday without technically having been eliminated from playoff contention. However, they ultimately decided to rest Kyrie Irving and four key role players (Josh Green, Tim Hardaway Jr., Maxi Kleber and Christian Wood), while star point guard Luka Doncic played only the first quarter. The Mavericks lost 115-112 and were eliminated from postseason contention. 

"We were fighting for our lives, and understanding this is a situation we're in, but the organization has made the decision to change," Mavs coach Jason Kidd said during his pregame media availability. "So, you know, we have to go by that and that's something that happens. So the guys that are playing, we got to go out there and put our best foot forward, and we talked about that this afternoon."

The Mavericks had a major incentive to lose on Friday. While their playoff hopes were still technically alive, the odds were against them. However, they owe their top-10 protected first-round pick to the New York Knicks. If they'd finished the season tied with the Oklahoma City Thunder or Chicago Bulls in the standings, they would've run the risk of losing their pick without having made the postseason in the process.

What exactly the NBA is investigating here is not fully clear. The Mavericks players on the floor nearly won the game despite the absence of their more famous teammates, and teams frequently sit their best players late in the season for the sake of draft position. Many teams build rosters designed to lose for the sake of a draft pick. While the unique circumstances surrounding the Mavericks were unique, tanking as a whole is not. 

It would therefore be difficult to prove that the Mavericks violated any sort of NBA rule that other teams have not violated themselves at some point. The NBA doesn't like tanking in any form, but it is almost impossible to legislate out of the sport entirely so long as the draft process still incentivizes losing.