When the Cleveland Cavaliers lose, they often looked bored, weary and old.

Not every player. Not all the time.

But in key parts of the game where the opponent is starting to run away with the verdict, the Cavs seem to say, “Forget it, we’ll get ’em tomorrow.”

This is not all the time. They can play inspired basketball. They did it a few times in the opening series against the Indiana Pacers, especially the dramatic Game 7.

They did in the series with the Toronto Raptors, especially the overtime victory in Game 1 when an exhausted LeBron James shot 12 of 30 from field. They won that game without James scoring in overtime.

They did it by blowing out Toronto in Game 4 to complete the sweep.

Do they have the energy to come back from being down 0-2 to the Boston Celtics and win the best-of-seven Eastern Conference finals?

I’m not sure.

After playing one of those dreaded “feel-out” games in the Game 1 loss to Boston where James scored only 15 points, he roared back with 42 points in Game 2.

But the Cavs still lost, 107-94.

Don’t blame Kevin Love. The All-Star forward scored 22 points. That meant James and Love combined for 64 of the Cavs’ 94 points.

I expect both to play well again when the series resumes at 8:30 p.m. Saturday at Quicken Loans Arena.

But how about anyone else?

Jordan Clarkson scored 10 points (mostly in trash time) in the opener. He didn’t play in Game 2.

Tristan Thompson and Kyle Korver are averaging 8.0 points in the series.

The starting backcourt of George Hill and JR Smith have scored a grand total of 12 points in 118 minutes, shooting 5 of 21. They have three assists.

Cavs Coach Tyronn Lue has had trouble adjusting to the moves of Boston Coach Brad Stevens.

At times, Lue has sounded emotionally drained this season as he’s battled some physical problems.

Meanwhile, Boston has been absolutely relentless.

This is the third time in four years that Boston has faced the Cavs in the playoffs. It’s the first time the Celtics have had a lead in the series.

They have only four players left from a year ago – Jaylen Brown, Al Horford, Terry Rozier and Marcus Smart.

Instead of the team relying on 5-foot-9 Isaiah Thomas to dominate the ball and trigger the offense, the Celtics are more athletic, more balanced in their scoring and shockingly improved on defense.

In the first two games, they have been a nightmare for the Cavs’ defense.

Lue likes to “take out a player” on the other team. The coach means target the opponent’s leading scorer and make it difficult for him to find open shots.

But Boston has six players averaging at least 10 points in the postseason. Four Celtics are averaging between 17-18 points.

After Game 2, Love marveled at how Boston had all five starters scoring at least 10 points.

The Cavs have had two starters in double figures in each of the first two games: James and Love.

Three Boston starters (Jayson Tatum, Brown and Rozier) are between 21-24 years old. We’re talking young, lively legs. The Cavs youngest starter is Love at 29.

While the Cavs have only four players left from their 2016 title team – James, Love, Smith and Thompson – they are playing huge roles on this Cavs edition.

At times, they just look worn down.

Is it the result of three consecutive trips to the NBA finals, three clashes with Golden State?

Is it knowing a fourth rematch is likely, and the Warriors are the most talented team (by far) in the NBA?

It’s hard to know.

I’m not writing off the Cavs. I am saying that since James returned in 2014, they have not faced a tougher Eastern Conference opponent than this edition of the Boston Celtics.