NBA Finals: Celtics take season’s worth of lessons into Game 5

BOSTON — The Celtics picked the most inopportune time to play their worst game of the season.

Boston’s 122-84 Game 4 loss to Dallas had all kinds of superlatives, and none of them were good.

It ended the Celtics’ 10-game playoff win streak. It was the Celtics’ lowest scoring output of the season and marked the first time the Celtics have allowed the Mavericks to eclipse 100 points in the series on a stellar night for Dallas stars Luka Doncic and Kyrie Irving.

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It also reminded the Celtics that putting a championship bow on what has been one of the franchise’s most successful seasons will require the same resilience they’ve shown during a postseason in which they haven’t lost consecutive games.

“It’s a learning lesson, for sure. Got to show up and show out every night. They’re not going to roll over,” Celtics reserve Sam Hauser said. “They’re down 3-1 now. They’re desperate. … They’re not going to make it easy on us.”

As humbling as Game 4’s loss was, history will be on the Celtics’ side for Game 5.

While Friday’s loss was the seventh time that the Celtics have lost by 20 or more points in the finals, they are 5-1 in the previous six.

The game Monday also falls on the 16th anniversary of Boston clinching its last championship in 2008.

“It’s a great opportunity to respond,” said Celtics forward Jaylen Brown, who finished Game 4 with a minus-19 plus-minus – his second-worst of these playoffs and third-worst of his entire playoff career. “We just regroup. We keep our same mentality, and we come out and get ready to fight in another battle on our home floor.”

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It’s also the latest chance for coach Joe Mazzulla to reinforce the lessons he has tried to instill in his team. Hauser recalled Boston’s Game 3 win when Dallas rallied to cut a 21-point fourth quarter lead to just one with less than four minutes to play.

“The Mavs were on that big run, the start of the fourth there. He came in and said, ‘That was great. That makes us hungrier,’” Hauser said. “He didn’t even focus on the win, he focused on that, which was cool. It keeps all of us grounded and knowing that we have more work to do.”

It was the same tone Mazzulla tried to set during the regular season.

Boston opened the season by winning its first five games before losing in overtime at Minnesota. Postgame Mazzulla expressed excitement for his team experiencing an opponent challenging it to play its best basketball. Following another loss two nights later at Philadelphia, the Celtics reeled off six straight victories.

In February, the Celtics lost on their home court to a Los Angeles Lakers team without both LeBron James and Anthony Davis. Then Boston reeled off a season-high 11-game win streak.

The Celtics are now just one more bounce-back win away from seeing those instances of adversity bear championship fruit.

If they need any more consolation — each of the Celtics previous three title-winning teams in 1984, 1986 and 2008 all lost with close-out opportunities on the road and then returned to win at home.

“Close-out games are hard. Close-out games are tough,” Brown said. “They always have been like that, and you’ve got to have extreme focus. You’ve got to come out and meet their intensity to finish things out.”

Jayson Tatum is expecting the TD Garden crowd to bring the energy to match the moment.

“I think it’s going to be as loud as it’s ever been in my seven years of being a Celtic,” he said. “Excited to go back home. Celebrate Father’s Day on Sunday and compete for a championship on Monday.”