According to a report from Tim MacMahon, the Mavs have already become frustrated with Jordan over what they see as "selfish play." Via ESPN:
Don't be deceived by DeAndre Jordan's solid statistics. He has been a major disappointment for the Mavs. He has rubbed teammates the wrong way with what they perceive as selfish play, the most blatant example being when he stole an uncontested rebound from Luka Doncic by putting his forearm in the prized rookie's back and tipping the ball away. Jordan's disinterest in playing help defense has been a big problem as Mavs opponents light up the scoreboard.
Free agent signings don't always work out, but it's especially bad when reports are leaking out about frustrations with a new player after less than a month of the regular season. That's what happens though when players don't only underperform on the floor, but cause locker room issues as well.
The Mavericks are currently 22nd in the league in defensive rating and are allowing opponents to shoot 62.4 percent at the rim, which is 23rd in the league. This isn't all Jordan's fault, obviously, but he isn't helping. And incidents like the one MacMahon mentioned -- pushing Luka Doncic out of the way for a rebound -- are particularly bad. Even Mark Cuban, who was sitting courtside, seemed annoyed by this play.
Jordan signed a one-year, $22M deal with the Mavs in the offseason, so the good news for the Mavs is they didn't make a long-term commitment. Judging by the first few weeks here, it doesn't seem like Jordan will be back.