At halftime of the Celtics’ game against the Heat on Wednesday, they honored 22 members of the 1966, 1976, and 1986 title teams. Bill Russell and John Havlicek walked to midcourt to standing ovations. Bill Walton and Kevin McHale followed soon after.

One by one, out came reminders of this franchise’s history, of its dominance. But inside the Celtics locker room, there was no celebrating or smiling or anything like that. Coach Brad Stevens quietly sat down in the middle of the room and kept his voice even as he addressed his team.

The Celtics had trailed by 26 points in the opening half before pulling within 22 at the break, and they’d left the court to boos on Fan Appreciation Night.

“What do we want to be?’’ Stevens asked. “There’s guys in this building that hung banners. Like, how do you want to play? How do we want to feel about ourselves?’ And we just looked different after that.’’

They were different, and they were dominant. They overwhelmed the Heat with their defense, their shooting, and their raucous crowd. And by the time the surge was complete, the Celtics had taken a 98-88 victory.

The 26-point comeback was the largest in the NBA this season. During the third quarter, Boston outscored Miami, 25-5, holding the Heat to an all-time franchise low for the period. The run was thorough, loud, and persistent.

“That’s embarrassing to have all these legends in the building and us playing that way,’’ guard Avery Bradley said. “In the second half I saw a few of them smiling . . . That’s what it’s all about. Going out there and playing Celtics basketball. We’re all a family.’’

Boston’s playoff position hinged on the results of the Hawks’ and Hornets’ games being played Wednesday, and when Atlanta lost and Charlotte won, all four of these teams finished with 48-34 records. The tiebreakers left the Celtics as the No. 5 seed in the East. They will play the fourth-seeded Hawks in the opening round.

In the end, the seeding is not favorable for Boston. The Celtics went just 1-3 against the Hawks this season, and if they get past them, the top-seeded Cavaliers will most likely be waiting. If the Celtics had lost this game, they would have faced the Heat — a team they are now 3-0 against — with the No. 2 Raptors on their side of the bracket.

Isaiah Thomas said he joked with president of basketball operations Danny Ainge afterward that he should have told the team so it could sub out the starters. Jae Crowder sat at his locker with his feet in a bucket of ice water and talked to Bradley, as the two tried to make sense of how this stirring comeback had apparently made their playoff path more difficult.

“We did all that for that? That was my reaction,’’ Crowder said. “We laid it on the line like that, for nothing? We could have taken the L?’’

A few reporters chuckled at that line, but Crowder did not.

“I’m being honest with you,’’ he said. “That was crazy. But It was very encouraging moving forward to get back to where we played and get the win. I think it will help moving forward.’’

And that had been Stevens’s point all along. After his team lost to the Hawks on Saturday and was throttled by the Hornets on Monday, he felt it was essential to find some footing entering the postseason. And if that was the goal, the mission was accomplished, no matter how unlikely it seemed after one half.

“I’d say it was one of the very few games I’ve coached where I wasn’t really paying attention to the score once the third quarter started,’’ Stevens said. “I was just paying attention to us. And I was just enjoying watching us play . . . It was just like, ‘Yes, thank you. Now we have a chance to move forward.’’’

The Celtics were out of sorts at the start, while the Heat were playing free and easy. By the time Goran Dragic hit a jumpshot with 7.9 seconds left in the first period, Miami had a stunning 35-13 lead, and some boos rained down.

Boston made just 5 of 24 shots in the opening quarter and was out-rebounded, 17-9. The Celtics played the Heat evenly in the second quarter, but when you’re down by 22, that’s not a recipe for a comeback. The Celtics trailed by as many as 26 points before going to halftime trailing, 62-38. But then came the third quarter, when everything changed.

With the Celtics trailing, 65-41, they went on a 22-2 runover the rest of the period, bringing the Garden crowd that had booed them earlier to its feet. The jump shots the Heat were drilling in the first quarter were suddenly nowhere close to going in, and Boston was on the attack.

The Heat made just 2 of 20 field goal attempts in the third quarter and did not attempt a free throw. Joe Johnson was the only Miami player to score a point. The Celtics, meanwhile, shot 52.4 percent from the field and went to the final period trailing just 67-63.

Boston continued its streak in the fourth quarter, as a Jonas Jerebko 3-pointer with 9:01 left capped a 12-2 burst that gave the Celtics a 75-69 lead. And unlike the Heat, Boston did not let this lead slip away.

Adam Himmelsbach can be reached at adam.himmelsbach@globe.com. Follow him on Twitter @adamhimmelsbach.