With back-to-back losses this week, the Miami Heat were not in their typically light mood on practice on Friday.

"There is a cloud over our team because we're not defending like we know we're capable of defending," LeBron James said. "We have some room for improvement. The good thing is we can be great. But right now, we're not good. We're not very good right now as a team and we've got to get to that point."

The Heat have allowed opponents score at least 100 points 11 times in 17 games. Last season, that happened 16 times in 66 regular-season games.

James insists the Heat are not willing to believe they can turn the switch on for the playoffs.

"Not for me," James said. "It's not for me. My motivation is well beyond hoisting one trophy. I'm not taking any shortcuts to get to that point, so I can't allow my teammates to take shortcuts. We've got to be better. I've got to be better. It's that simple."