MIAMI - Dirk Nowitzki took the blame for the Mavericks' fourth-quarter woes that put them in a seven-point hole heading down the stretch.Nowitzki was on the court with Dwight Powell, J.J. Barea, Devin Harris and Dorian Finney-Smith.That group, which had been effective during the three-game winning streak, was on the court for just 2:58.