Stress levels around the NBA typically go up a notch or two the day before the trading deadline (Thursday, 2 p.m.). For the players, it’s a nuisance. As O.J. Mayo said Tuesday: “You can’t really believe anything until the breaking news shows up at the bottom of the screen.” Donnie Nelson has burned up enough cellphone minutes to char-fry anybody’s monthly bill. The Mavericks’ president is as plugged in as anybody regarding what’s going on and who is likely to be involved in deal-making before the deadline. “There’s certainly chatter,” Nelson said Tuesday. “And there will be some things that get done. But there are a lot of teams that are hesitant to do anything that they feel is nothing more than a marginal upgrade.” Lump the Mavericks into that grouping, by the way. They can make plenty of deals. The offers are there. But they have to take back salary for next season to make any of them happen. And that’s where most of their conversations end. Atlanta has let it be known that Josh Smith is available. And Devin Harris, among others, also could be on the move. They remain the most likely to be dealt in the final hours before the deadline. Another team open to dealing is Milwaukee, which has dangled Monte Ellis. But one player who may no longer be available is Samuel Dalembert, the center who most certainly would be appealing to the Mavericks if he could be had. His expiring contract, at $6.7 million, would be perfect, but Dalembert has begun playing more since Scott Skiles replaced Jim Boylan as coach.