Pistons deal blow to Celtics

It’s the point when unstable teams start pointing fingers.

“They’re frustrated in there,’’ said coach Doc Rivers. “And I said, ‘It’s great to be frustrated, but we’ve got to do something about it.’ ’’

It’s a point the Celtics, now losers of five of their last seven, have not faced in the rejuvenated era that started two-plus seasons ago. It’s the point at which they now find themselves, having dropped to 27-13 by compounding injuries with inconsistency and now simmering frustration.

“These are problems you shouldn’t have when you have the goals that we have,’’ Rivers said. “I know it’s the dog days and everybody’s going through stuff right now, but we’re self-imposing our [issues] right now.’’

The common thread in the Celtics’ recent downturn has been third-quarter letdowns, and last night was no different.

After seemingly burying themselves in the first quarter by committing 10 turnovers that the Celtics turned into 15 points, the Pistons, as desperate as they were depleted, fought back in the third behind Rodney Stuckey’s all-around play (27 points, 11 rebounds, 6 assists) and Jason Maxiell’s shooting (12 points) and defense (two steals and a block).

Richard Hamilton (12 points, eight assists) returned to the Detroit lineup after missing Monday’s loss to New York with an upset stomach, and Ray Allen spent so much time chasing him on defense that he was ineffective on offense (8 points on 3-of-10 shooting).

The Pistons used the Celtics’ sloppy third quarter to climb back into the game, then dealt Boston a body blow with a 13-0 fourth-quarter run that started with a bucket down low from Charlie Villanueva and also included Villanueva swirling in a 3-pointer in front of the Celtics’ bench. Villanueva then sealed the game with another three with 55.1 seconds remaining.

The Celtics’ offense went numb after the break, mustering just 30 second-half points on 9-of-30 shooting.