MIAMI — As the Boston Celtics stare down the possibility of being swept out of the Eastern Conference finals, guard Malcolm Brogdon said the team’s issues against Miami in this series are a symptom of season-long issues against consistent opponents, adding that Boston’s identity has “waned all year long” and that its defense has slipped.

“I think it’s teams that have a strong identity,” Brogdon said during an off-day availability session Monday afternoon at the team’s hotel ahead of Game 4 Tuesday night. “I think Miami is one of the teams, one of the few teams in the league — Miami, Denver, there are only a few of them — that have a really strong identity and they play by it every single night. They’re super committed to it.

“And, for us, our identity has waned all year long. We’ve been trying to figure out who we are, because I think we’re such a great, talented scoring team, but when we don’t make shots, we got to rely on our defense, and our defense isn’t consistent every night.

“So, playing a team that’s very consistent and disciplined, we struggle.”

Boston certainly has struggled over the past week, going from the high of Jayson Tatum scoring 51 points to knock off Boston’s oldest rival, the Philadelphia 76ers, in the Eastern Conference semifinals, to losing two straight games at home to Miami to begin this series with fourth quarter implosions before being run out of Kaseya Center on Sunday night in Game 3 under an avalanche of Heat shot-making.

After Sunday night’s demoralizing loss, Celtics coach Joe Mazzulla admitted Boston’s defense has regressed. After being ranked second in the regular season, Boston’s defense is allowing three more points per 100 possessions in the postseason and has dropped to 10th among playoff teams. But Brogdon said Monday that the team hasn’t been consistent defensively all season long, and that issues that began to crop up against the Atlanta Hawks and 76ers over the first two rounds of the playoffs are coming back to haunt the Celtics now.

“We haven’t been consistently great defensively all year long, and that was the team’s identity last year,” Brogdon said. “I think that’s slipped away from us. We’ve had spurts where we’ve been great defensively, but not consistently.

“And, honestly, we’ve struggled in every series we’ve played. So, now we’re playing a team that’s playing as if they’re the best team in the league, and they’re just incredibly disciplined, incredibly consistent. And I think we’ve struggled with teams that are consistent on a possession by possession basis every night.”

The Celtics have struggled with virtually everything in this series. Jaylen Brown is shooting 37% from the field, and 2-for-20 from 3. As a team, Boston is shooting under 30% from behind the arc for the series.

To Brogdon’s point about shotmaking, the most telling stat about Boston’s season is that the Celtics are 36-2 when they make 40% of their 3-pointers, and are 29-31 when shooting below that, which the Celtics have now done in each of the first three games of this series.

All of that, though, is now in the rearview mirror for the Celtics, who face the same uphill battle their forever rivals out west, the Los Angeles Lakers, do against the Nuggets: trying to become the first team in NBA history to recover from a 3-0 deficit in a best-of-7 series to advance.

The prior 149 teams to get in that position have failed to come back. Only three of them have even forced a seventh game.

But Mazzulla said that he and his players can’t do anything but focus on the immediate task in front of them: getting a win in Game 4 to extend this series by another game, and another 48 hours.

“I think that’s the opportunity that we have,” Mazzulla said. “We have to do that. We can’t get caught up in worrying about the task at hand. And if we don’t take care of one game, then the other games don’t matter.

“So we just have to have a narrow-minded focus on that.”

And, to do that, Boston is going to have to do much better defensively than it did in Game 3. The Celtics allowed the Heat to shoot 57% overall, go 19-for-35 from 3-point range and romp all over the Celtics in what essentially was a 48-minute celebration of Miami’s truly stunning turnaround over the past several weeks.

The Heat, who trailed the Bulls inside the final three minutes of the second play-in game here — after losing to Atlanta in the first one, also at home — are now just one win away from the NBA Finals, and from having knocked off the teams with the two best records in the NBA — Milwaukee and Boston — en route to getting there.

But until they’ve lost four times, the Celtics still — at least technically — have life. And, Brogdon said, there has to be a first team to pull this off, and that’s what Boston is hoping can carry it to a first win in this series in Game 4.

“Absolutely,” he said. “That’s the approach you have to take.

“We still believe we’re the better team. We have not played like it in these three games. But there is always a first.”