Celtics are at a crossroads

These are not the Boston Celtics of yesteryear. In fact, they are not the Celtics from the 2007-08 NBA championship season who defeated the Lakers in the Finals.

These Celtics are a team that’s old and slow, that has aging stars in Ray Allen (34), Kevin Garnett (33) and Paul Pierce (32).

These Celtics are failing to execute when the game hangs in the balance, as they did Sunday afternoon against the Lakers in a 90-89 loss at TD Garden.

These Celtics can’t get defensive stops as they have in the past, this time watching Kobe Bryant nail a 16-foot jumper over Allen with 7.3 seconds left.

These Celtics can’t execute on offense, demonstrating that anew Sunday with a late charging foul against Pierce that was a big turnover with Boston ahead by one point, and a last-second missed shot by Allen that could have won the game.

This is what the Celtics have become, a team that has more questions than answers.

They have lost three consecutive games, all to some of the NBA’s better teams -- Orlando, Atlanta and the Lakers -- teams they used to regularly beat two seasons ago. Boston is 4-11 in its last 15 games.

“The thing that -- I don’t know if concern’s the right word -- is we haven’t been able to get timely stops to end games,” Coach Doc Rivers said. “The Atlanta game came down the stretch and they scored every time. The Orlando game came down the stretch and they scored every time. And tonight.”

The Celtics led the Lakers by 11 points with nine minutes to play.

They scored eight points the rest of the way. They turned the ball over five times. They gave up 20 points the rest of the way.

That vaunted defense the Celtics used to play is a thing of the past.

“We don’t lack any confidence,” said Garnett, who had only 10 points, nine rebounds and five turnovers. “Our spirits are high. We have a little saying, to work hard.”

That’s what it will take for the Celtics the rest of the way.

They are in fourth place in the Eastern Conference.

Garnett, the heart and soul of the Celtics, sat out 10 games this season because of a hyper-extended right knee.

Sunday was only his fifth game back since sitting out and he still doesn’t look quite the same.

He wore a long white sleeve from his ankle up to his knee.

He didn’t run with his usual fluid motion against the Lakers.

His defense was shoddy.

Rivers was asked whether Garnett can be held to the same standards defensively as two years ago when he was defensive player of the year

“Yeah, I can,” Rivers said. “Not right now. Really none of our guys who have come back [from injuries], I can’t hold any of them to their normal standards right now.”

broderick.turner@latimes.com

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