BOSTON -- As Jayson Tatum trudged to the podium inside TD Garden long after the Boston Celtics saw their season come to an end with a 103-84 loss in Game 7 of the Eastern Conference finals, there was a visible limp from the sprained ankle he suffered on the opening play of the game.

"It was just frustrating that I was ... a shell of myself," Tatum said after he played 42 minutes and finished with 14 points on 5-for-13 shooting in the loss, which ended the Celtics' season and also denied them the chance to become the first team in NBA history to overcome a 3-0 series deficit.

"It was tough to move. Just frustrating, it happening on the first play."

There was much for the Celtics to be frustrated about, beginning with Tatum having the bad luck of landing on Heat guard Gabe Vincent on the first possession of the game. But that was far from the only thing.

The Celtics followed up their worst 3-point shooting game of the season (7-for-35) in Game 6 by shooting 9-for-42 in Game 7 to equal their second-worst shooting performance of the season. Boston played seven games this season in which it shot under 26% from 3-point range, and Game 6 was the only one the Celtics came away from with a win.

Meanwhile, Boston watched as Caleb Martin continued his series-long assault on the Celtics' defense, going 11-for-16 and scoring 26 points, while Eastern Conference finals MVP Jimmy Butler contributed 28 points, 7 rebounds, 6 assists and 3 steals.

The Heat shot 14-for-28 from 3-point range Monday night and were 28-for-58 over the final two games of the series.

"We got punked," Celtics forward Grant Williams told ESPN. "We didn't play our game from start to finish. Defensively, we just lost it all, and then offensively we were scrambled and trying to do everything ourselves and just didn't go our way.

"You hate to have that be the end of your season, especially with the fight that we've shown. But shots didn't fall either, so that didn't help ... it's just tough."

It was a resounding thud of an ending to a season that entered Memorial Day with sky-high expectations, after the Celtics had recovered from blowing the first two games of the series here at home, and then getting blown out in Game 3 in Miami, with three straight impressive performances to move to the brink of history.

But after Derrick White's remarkable putback at the buzzer gave the Celtics a magical push into a do-or-die Game 7, it seemed their luck ran out.

Even after Tatum sprained his ankle, Boston was off to a quick start, taking an early 9-4 lead. But then the Celtics kept missing ... and missing ... and missing. And Miami responded with an 11-2 run and never looked back, ending the quarter up 22-15.

Boston never got closer than that 7-point margin the rest of the game.

"[We were] missing shots, and then they're coming down and hitting shots," Marcus Smart said. "It puts a lot of pressure on our defense to get stops. And they were hitting some shots and they got in a rhythm and we weren't making ours."

Jaylen Brown, meanwhile, had a dreadful game, finishing with 19 points on 8-for-23 shooting to go along with 8 turnovers, as his repeated forcing of the action offensively was symbolic of how Boston's entire night played out.

Now, the Celtics head into the offseason after falling short of a return trip to the NBA Finals -- something the team had stated as its goal going all the way back to last June's Game 6 loss to the Golden State Warriors -- and will have to figure out where to go from here.

Coach Joe Mazzulla will have a full offseason of preparation -- something he didn't have heading into his first season, after being placed in the job days before the start of training camp after his predecessor, Ime Udoka, was suspended for violations of team rules.

Both Tatum and Brown praised Mazzulla for how he handled the season.

"I give Joe my respect," Brown said. "Tough situation to be in. And he took it and he took it head-on and ran with it. We had two rookie head coaches in the last two years, and Joe picking up from Ime as an interim starting off and then progressing as being the head coach, just fully took that challenge on and led us to this point. That's a tough position for a guy to be in. It's a tough position for a team to be in, coming off of a Finals run, but we didn't make any excuses and I'm not making any excuses now.

"We came up short. But I still give my respect to our coaching staff and that group that we had on the floor."

As for his future, Brown -- who is eligible to sign a five-year, $295 million supermax extension this summer after making second-team All-NBA -- said he wasn't sure about his thought process heading into the summer.

"I don't even really know how to answer that question right now, to be honest," Brown said. "My thought process is take it one day at a time, focus on getting better. Focus on what the future holds and see where we are from there."

White, meanwhile, said he's going to get an MRI on his left leg after injuring it in the second half.

"I mean, I'll be fine," White said. "I'm not too worried about it. But I'll find out more tomorrow."

Overall, the Celtics left TD Garden with a sense of regret. After a 57-win regular season, advancing to the East finals for a fifth time in seven seasons, and climbing all the way back from a 3-0 hole, their season fell five wins short of raising an 18th banner to the rafters.

And while both Mazzulla and the players raved about their group's toughness, it wasn't enough to make history Monday.

"You can't go through life talking about what you could have, you should have done," Tatum said. "S--- happens and the past is the past.

"We fought like hell to give ourselves a chance today. Just not the outcome that we anticipated."