"We have been careful to distinguish between efforts teams may make to rebuild their rosters, including through personnel changes over the course of several seasons, and circumstances in which players or coaches on the floor take steps to lose games," Silver wrote in the memo, obtained by USA Today Sports.
"The former can be a legitimate strategy to construct a successful team within the confines of league rules; the latter -- which we have not found and hope never to see in the NBA -- has no place in our game. If we ever received evidence that players or coaches were attempting to lose or otherwise taking steps to cause any game to result otherwise than on its competitive merits, that conduct would be met with the swiftest and harshest response possible from the league office."
Cuban made headlines earlier this month when he revealed during a podcast that he told members of the Mavericks that "losing is our best option." The league responded Feb. 21 by fining him $600,000, citing "public statements detrimental to the NBA."
Silver mentioned "integrity" on multiple occasions in the subsequent memo, portions of which were published Wednesday as part of a USA Today report. He said the league doesn't believe the Mavericks are tanking.
The Mavericks lost 111-110 in overtime to the Oklahoma City Thunder on Wednesday night to fall to 19-43, just a half-game ahead of the Sacramento Kings and Orlando Magic (18-43) for the worst record in the league. The bottom eight teams in the league are separated by just 2 games in the standings.
The team with the worst record will have a 25 percent chance of landing the No. 1 pick in this year's NBA draft.
Starting with the 2019 draft, the three teams with the worst records will share a 14 percent chance of getting the No. 1 pick, a move intended to lessen the incentive to lose at the end of the season.
"We have no basis at this time to conclude that the Mavericks team is giving anything less than its best effort on the court, and Mark has assured us that this is not the case," Silver said in the memo. "But even a suggestion that such conduct could be occurring is obviously damaging to our game, as it creates a perception of impropriety. It is also extraordinarily unfair to the players and coaches who are, in fact, competing at their highest possible level every night.
"You are therefore advised to avoid such statements, and to pass along this admonition to all other key personnel in your organizations. We will continue to monitor closely the play of all teams during the remainder of the season."