NEWARK, N.J. — Everyone got a glimpse of what the Nets would look like once they’re whole, but it lasted about a half.
 
Then in the second half of Tuesday night’s game, and particularly the fourth quarter, the Nets looked like everyone probably expected them to this season.
 
They struggled offensively, missed free throws, couldn’t get enough stops and had overall  poor execution on both ends. What was once a 14-point lead turned into a 91-88 Nets’ preseason loss to the Celtics. These were the Celtics without Kevin Garnett, Paul Pierce and Ray Allen for the entire game and Rasheed Wallace for the fourth period.
 
But it doesn’t matter who the Nets are playing. They can’t have the kind of letdown they had in a game they should have won.
 
Maybe it’s different, maybe the execution is better if Devin Harris didn’t leave at halftime with a strained right groin because the Nets didn’t have a go-to guy on the floor down the stretch.
 
Chris Douglas-Roberts, who continues to impress, was the most productive with six of their 11 points. But he missed two critical free throws in the fourth, including one with 1:29 left that would have put the Nets up two.
 
The Nets missed five foul shots overall and gave up a crucial rebound off a Celtics’ missed free throw with 13.1 left.
 
Rajon Rondo’s brick wound up in Glen Davis grasp, resulting in one made free throw for the man known as Big Baby. Seconds earlier, Davis rejected a Courtney Lee drive that could have given the Nets a one-point lead.
 
Even without their Big Three and a big fourth, the Celtics know how to win. The Nets don’t yet.
 
“The Celtics now have developed a culture where you saw their intensity level rise up,” coach Lawrence Frank said. “For us, we know what it feels like. We’ve been there. Now we’re trying to reestablish.
 
“The thing that’s disappointing is we weren’t able to raise our level of intensity. Regardless of who’s on the floor — they were without some of their best players. So it’s not about playing close. You get these experiences, but we have to continue to get better regardless of the score. You like to win, but we can’t get outworked.”
 
The ending ruined what could have been a very good night for the Nets. They played at the Prudential Center for the first time — perhaps a temporary home away from home until Brooklyn is built — and had a good crowd of nearly 13,000.
 
Playing with a full complement of players for the first time as Lee and Harris were on the floor for the first time together, the Nets started fast. They showed what their strength is going to be — running the floor, getting into the passing lanes, creating shots for each other.
 
With Harris, Lee, Douglas-Roberts and Brook Lopez combining for 45 points on just 25 field goal attempts, the Nets raced out to a 60-47 lead at the half.
 
“Guys running the break, getting out, getting ahead, passing it ahead and we finished at the rim, I thought we had a good pace,” Harris said. “With CDR and Courtney out there together they’re good wings. I thought those guys were tremendous even in the second half. That’s more encouraging to see when our wings are playing that well.
 
“That allows me to be a little bit more free and give those guys the ball and it takes pressure off myself and Brook.”
 
They all finished with solid numbers as Lee had 21 in his first start and Douglas-Roberts, who started five-of-five, had 19 and Lopez 17 and 10. But those numbers mean little because of the ending.
 
All it means is the Nets can be fun to watch when they’re all together, but they’ve been banged up a lot in the backcourt already and continue to be. They hope that — as much as the endgame — isn’t a sign of what’s to come.
 
Al Iannazzone covers the Nets for The Record (Bergen County, N.J.).