Brad StevensThe defining trait of the Boston Celtics in the Kevin Garnett era was the consistency of their intensity. With the Big Ticket barking orders from the paint, the Celtics proudly proclaimed that they brought it for a full 48 minutes, that they never took a play off.

Except, occasionally, they did. Every human being, over the course of his working day, week, month or year, has a lapse in concentration or effort now and then. Garnett and the Celtics weren’t superhuman; they suffered the rare moment of weakness, too.

But when Paul Pierce or Ray Allen is around, a team can afford a hiccup or two. No Celtics fan needs to be told about all the times Pierce bailed out his team with a late shot.

Of course, Pierce, Garnett and Allen are gone now. Missed plays are far costlier for this season’s Celtics, who aren’t incapable of winning if they truly play a flawless game. It’s just that, mostly, they haven’t.

“Obviously, we’re a young team, so-called ‘rebuilding,’ so the margin for error, of course, is going to be a little smaller,” forward Brandon Bass said. “We understand that. We’re just trying to get better each and every game, and just try to find the positive, no matter what the results are.”

The Celtics dropped their fifth consecutive game Monday and their fourth in a row in which they were in position to win in the fourth quarter. Yet they scored 10 points in the final 12 minutes, matching Bulls center Joakim Noah’s scoring output in the quarter, and were saddled with their most lopsided loss against Chicago this season.

Still, the Celtics haven’t been totally, abjectly awful. They’ve been in games. They just haven’t been closing them out.

The Celtics are 13-25 in games decided by seven points or less, revealing just how slim their margin for error is. It might seem like an arbitrary cutoff, but seven points reliably signifies a tight contest. Intentional fouls and garbage-time lineups tend to stretch four-point nail-biters into comfortable-looking victories in the end. (Monday’s one-point game ballooned to 14 by the time the final horn blew.) Clearly, that is happening to the Celtics more than they would like.

“We’ve just got to keep trying to find a way,” guard Rajon Rondo said after Sunday’s loss. “It’s a little deja vu, but I’m not discouraged at all. You can look at it a couple different ways, but, you know, we hate losing. We’ve got to find a way, eventually, to win some of these games. We’re just not closing games the right way.”

They have succeeded at times, such as when they outscored Dwyane Wade and the LeBron James-less Miami Heat 48-37 in the second half of their victory in mid-March. There is not much the Celtics can accomplish with just eight more games on the schedule, but reanalyzing their execution and philosophy late in games might be worthwhile.

“Certainly, when we re-evaluate our season when it’s over, we’ll go back and talk about the margin,” coach Brad Stevens said. “We’ll obviously talk about, ‘This is how far away you are.’ Obviously, some teams have larger margins than others, so it doesn’t present itself quite as much, but it is a testament to these guys playing together. It’s also a testament to the new guys we’ve brought in, who have just kind of fit in.

“Hey, (Jerryd) Bayless and Chris Johnson are playing great. I think there’s a lot of positives in what we’re doing, but it is frustrating. I don’t think we can hide from our reality.”