Halfway through the season, the Celtics are 15-17, good for the eighth and final playoff spot in the Eastern Conference.

“There’s not a lot of consistency,” Rajon Rondo said during yesterday’s All-Star media session. “That’s why our record is what it is. We may play well for two or three quarters and then go in a lull where we don’t score the ball, not a lot of ball movement, getting outrebounded, not taking care of the glass. I think we’ve lost maybe over half of our games by just not being disciplined, just simple mistakes in the fourth quarter.

“I know I have a couple of those mistakes, just leaving guys in the corner for 3-point shots, double-teaming when it’s not needed, just little mistakes like that where we’re not being disciplined and we’re beating ourselves.

“I think for us basically we need to stay disciplined. We need to rebound the ball better and take care of the ball and just keep sharing the ball offensively. I think those three things are pretty simple, but we haven’t found a way to do it consistently.”

Paul Pierce echoed similar themes as he listed his team’s deficiencies.

“It’s little things that are really killing us,” Pierce said. “But I’m attributing a lot of that to the lack of practice time. But also it’s about the discipline and understanding what we’re trying to do. You know, when we come out of timeouts we need to have guys listening and understanding what (coach) Doc(Rivers) is telling us and go out and execute.

“That’s the most frustrating part about it. Hopefully we have a better focus going into the next half of the season to where we’re concentrating on all the little things, to where we don’t have execution mishaps, especially after the timeouts.”