The Clippers fell behind by 17 early in the third quarter before running off 15 straight to cut it to 66-64 midway through the period. But McDermott hit a three-pointer in transition and added another during a 12-0 response by the Knicks that gave them a 78-64 advantage with 4:11 remaining in the period.
The game was tied at 20 after one quarter, but the Knicks opened a double-digit lead late in the half after a 9-2 spurt and were ahead 56-44 at the break.
The Clippers traded Chris Paul in the offseason and the search for reliable guard play remains.