The Wizards matched their opponents at the start of the game, but allowed the home side to power ahead in the second quarter.
The head coach told reporters: "That's just commitment to rebounding, just not ready. I don't know what to say about that. Inexcusable."
Shooting guard Bradley Beal added: "We played so aggressively and so hard against [Oklahoma City Thunder]. It was like game seven of the finals or something. Then now, we come out tonight and not have that same mentality."
The Wizards have a 2-5 record so far this season.