WALTHAM, Mass. (AP) – Paul Pierce and Wally Szczerbiak laughed as they shot free throws at the end of practice Tuesday. Coach Doc Rivers talked about his team not giving up.

The Boston Celtics’ mood is positive, their effort exemplary – and their record is the worst in the NBA.

“I’ve seen a lot of good signs. The problem is they’re not consistent good signs,” Rivers said after the workout that followed the latest close loss, 92-89 Monday night to Orlando, and dropped the Celtics to 1-6. “That’s probably the most difficult thing with this team.”

That’s hardly a surprise to Rivers as he tries to mold a young team into a winning one.

The jump from high school that Al Jefferson, Kendrick Perkins and Gerald Green made is huge. Even rookie Rajon Rondo, who played two years in college at Kentucky, is experiencing rookie ups and downs.

All, though, have great potential, along with mental lapses and intermittent commitment to defense.

Four days after the death of Red Auerbach, who was part of all 16 Celtics titles as coach or front-office leader, the Celtics lost their opener to New Orleans, 91-87 after trailing by one point with 2 minutes left.

That started a trend.

In the latest loss Monday night, the Celtics led by one with 2 minutes left.

Danny Ainge, the Celtics executive director of basketball operations, takes some pleasure in the close outcomes. But not Rivers.

“Danny and a couple of guys are saying, “Hey, man, we’re right there,’ ” Rivers said. “I said, “I want to win. I don’t want to be right there.’ And I want our guys to understand it, that playing these close games, it’s not some kind of victory for us.”

He pointed out, though, that with four minutes left in all seven games, neither team led by more than six points.

“Our guys have proven that they won’t go away and now we’ve got to prove that we can close the deal,” Rivers said.

That competitiveness keeps players upbeat.

“We realize that we’re close and we’re a couple of mistakes from turning these losses into wins,” Pierce said. “That’s why we still keep it positive around here. Guys walking in with their heads up.”

Now if they can only develop some consistency.

Rivers didn’t use Rondo in a 110-108 win over Charlotte, then had him on the court for more than 24 minutes in the next game in which he had 13 points and three steals.

Perkins scored a total of six points in the first three games as the starting center then came off the bench to score 10 in the fifth game.

Even Pierce has struggled, despite leading the team in points, rebounds and assists. Against Orlando, he missed 14 of 20 shots and the Celtics lost by three.

“We held a team to 92, we should win that game. You have a chance to win that game,” Rivers said, “and our offense was down. It’s one thing or the other. That’s where we are right now.”

But he thinks the mistakes are correctable – failure to block out or get back on defense, poor communication at times.

“It’s OK to be frustrated. That’s part of the game. Guys don’t like to lose,” Pierce said. “We’ve got to do the little things to turn these close losses into wins and these guys realize we’re not that far away.”

Their next two games are at home against Indiana and Portland on Wednesday and Friday nights.

Center-forward Al Jefferson, their third-leading scorer, expects to attend the Portland game after his appendix was removed last Wednesday.

He thinks he may be able to play in a game next week once he gains back some of the 10 pounds he lost since the surgery.

He weighs 250 now, a lot more than he did last season when he missed much of it with an ankle injury

“I’d have killed to be 250 then,” he said with a smile. “I haven’t been 250 since ninth grade.”