Paul Pierce, on Thursday with WEEI’s Dale & Holley, might have said the Celtics are ‘built for the playoffs’ but his coach wants them to be a fine-tuned machine when they get there.

To that point, Doc Rivers outlined two areas he believes his team has improved since the All-Star break and one more he believes still needs work before the second season begins.

Rivers told reporters following Thursday’s practice that the team has cut down on its turnovers since the break and has done a better job of rebounding in recent games.

But the one area he still feels his team needs work on its weak-side defense. In other words, Rivers wants to see more green and white shirts flying to the open shooter and not allow wide open shots, especially from three-point range.

That was particularly evident on Wednesday when Jeff Green nailed back-to-back three-pointers in the final two minutes to seal Oklahoma City’s 109-104 win over the Celtics.

“Turnovers are going down but we’ve had the sporadic bad game,” Rivers said. “We’re rebounding better, we’ve had the sporadic bad game. And then there’s the weak-side defense.

“To me that’s the biggest concern, a guy is going to get beat off the dribble, that next guy being there to take the charge and the next guy being there to get his body in the way and then the next guy getting on that guy’s body. That’s the next step we have to make.”

Rivers also said his players were more upset with three free-throw discrepancy than he was.

“I thought we could’ve gone to the line more but I thought we could’ve been more aggressive going to the basket as well since we took a lot of threes,” Rivers said. “I thought they were complaining more they were playing good defense on some of those and they were playing good defense.”