Howard, the 29th overall pick in 2003, was in his seventh season with Dallas. Gooden, signed by Dallas last summer, will be going to his eighth team in eight NBA seasons. Butler, a two-time All-Star, averaged 16.9 points and 6.7 rebounds in 47 games this season.
It is a significant move for the Southwest Division-leading Mavs (32-20). "It makes us significantly better," owner Mark Cuban said. For the Wizards (17-33), the trade appears to signal the breaking up of a team that was expected to contend for a playoff spot.