BY TOM HABERSTROH

March 25 is the NBA trade deadline, All-Star Weekend is traditionally when those talks really start heating up. In talking to more than a dozen sources in front offices around the league, there are some obstacles to that schedule this year:

• James Harden, Russell Westbrook, John Wall, Derrick Rose … a lot of this season’s trades have already happened.

• The new play-in tournament has more teams hopeful of making the playoffs, and thus hanging on to talented players who might have been traded in years past.

• The Clippers, Nets, Lakers, Bucks—contenders who would love to improve—have almost nothing to trade.

• Front offices have been so taxed managing COVID that a fraction of the typical trade calls have taken place.

Also, nobody knows how good their team is. So many players have lost games to COVID protocols and injuries that teams are still unsure where they fit in the NBA landscape. For example: the Heat are defending East champions, and a game from needing a play-in to make th…