A fan is handcuffed by Boston police after allegedly throwing a water bottle at the Kyrie Irving of the Brooklyn Nets as Irving left the court following Brooklyn’s 141-126 win over the Boston Celtics at TD Garden on Sunday night. Elise Amendola/Associated Press

Things were looking up in Boston on Saturday. To be more precise, players and coaches were looking up.

At Fenway Park and TD Garden, they couldn’t help but gaze at the sea of humanity that had returned after virtually all COVID-19 related restrictions were lifted across the city and state.

At Fenway Park, more than 25,000 fans braved the rain and cheered on the Red Sox to a 3-1 win over the Miami Marlins. Less than an hour later, a full house awaited the Bruins for Game 1 of their second-round playoff series against the New York Islanders.

The new “Roaring 20s” got off to a roaring start.

The crowd at Fenway was nearly three-times bigger than any gathering of Fenway faithful in the last 20 months. It came to life when Adam Ottavino struck out Miami’s Garrett Cooper to end the seventh inning with the bases loaded in a 2-0 game.

“Kind of an out-of-body experience there,” Ottavino said after the game. “Glad I was able to make the pitch. I just kind of blacked out.

“I usually just keep my head down and make my pitches. My wife always says, ‘What are you looking at?’ I’m always just like, ‘I’m looking at the ground and then the catcher and that’s it.'”

Not this time. Ottavino stared up at the fans in amazement as he shouted in exaltation. This from an 11-year MLB veteran who spent his last two seasons in New York pitching for the Yankees. Even with that type of experience, Saturday’s crowd came as an unexpected jolt of energy.

It was more of a thunderbolt at the Garden. The crowd was roaring before the Bruins took the ice, and was shaking the rafters by the time David Pastrnak delivered his third goal of the game in the third period.

“You could feel the energy this morning,” said Pastrnak. “We were all excited. In the warmup, it felt like 22 players playing the first NHL game … definitely a different game with the fans.”

A night later the Garden fans were a big part of the story again, but for all the wrong reasons. A fan was arrested Sunday night after Brooklyn Nets star Kyrie Irving (the former member of the Celtics) had a water bottle thrown at him following Brooklyn’s 141-126 win in Game 4.

It was an unfortunate reminder that not everyone in every crowd is adding positivity.

After the game, and the incident, Irving lamented that fans often treated players “like they’re in a human zoo. Throwing stuff at people. Saying things. There’s a certain point where it just gets to be too much.”

Irving might be one of the least popular players in Boston right now, but he is absolutely right. The fan who allegedly threw the bottle doesn’t represent the vast majority of us. Yet this incident overshadowed what should’ve been a feel-good weekend as life in Boston took a big step toward normalcy.

For the past year or so we’ve talked about what the “new normal” would be like after COVID. Let’s hope the new normal features fewer stupid acts like we saw from one fan Sunday night.

Tom Caron is a studio host for Red Sox broadcasts on NESN.