CLEVELAND — After Game 1 of the NBA Finals, in which the Golden State Warriors cruised to an easy victory over the Cleveland Cavaliers, Klay Thompson was frustrated. While the all-star shooting guard’s defense had been a big factor in Golden State’s victory — Cavaliers shooters had gone just 1-for-12 with him covering them — Thompson had shot just 3-for-16, continuing his postseason slump.

One of the NBA’s best shooters, Thompson averaged 13.8 points per game while shooting a very pedestrian 36.6 percent from the floor through 13 postseason games — including an unthinkable 33.8 percent from 3-point range. All of those numbers were a far cry from Thompson’s regular season averages of 22.3 points on 46.8 percent shooting and 41.4 percent from behind the arc.

All of it was weighing on the 27-year-old, who desperately wanted to snap out of his slump. And that, he decided, was the problem heading into Game 2 of the NBA Finals: He was thinking too much. And, after scoring 22 points on 8-for-12 shooting — including 4-for-7 from 3 — in Golden State’s 132-113 Game 2 victory, Thompson admitted a different approach made all the difference.

“Yeah. Relax,” Thompson said with a smile when asked whether he’d done anything to snap himself out of his funk. “I just relaxed tonight, and took good shots in rhythm. That’s the key for me, and I need to do the same thing in Cleveland.

“Just relax, man. It’s just basketball.”

Playing on a team with Stephen Curry, the NBA’s best shooter, Kevin Durant, one of its best and most versatile players, and Draymond Green, one of its biggest talkers and best defenders, it’s easy for Thompson to be overlooked. He doesn’t seek the spotlight — in fact, he often does his best to minimize his interactions with the media — and doesn’t have the kind of eye-popping moments on a regular basis as his fellow Warriors all-stars.

But Thompson’s two-way contributions have become critical to Golden State’s identity at both ends of the floor. And if he continues to put the slump behind him, beginning with Game 3 at Quicken Loans Arena tonight, it’s hard to see how the Cavaliers can get back into this series.

“Klay played so well in Game 1, without shooting well,” Warriors Coach Steve Kerr said. “And, to me, that usually indicates that the ball’s going to go in. His defense was tremendous in Game 1, his ballhandling, his passing. I thought he played a great game.

“I just felt like he was poised to come out and make some shots tonight, and he did. And his defense again was tremendous. I thought Klay, he guards so many people out there and he has such a responsibility with Kyrie (Irving) and switching onto LeBron (James), and I thought he was fantastic.”

Thompson has become a household name because of his shooting stroke. His partnership with Curry in Golden State’s backcourt — complete with the perfect nickname of “Splash Brothers” — gives the Warriors the best shooting combo in the league.

But Thompson’s defense is his main asset. He takes on the top defensive assignment on the perimeter for the opposition on a nightly basis, meaning Golden State can put Curry on a lesser threat and allow Thompson — with his 6-foot-7 frame and long arms — to give one of its opponent’s best scorers plenty of trouble.

“He really plays for his teammates,” Warriors General Manager Bob Myers said before Game 2. “Defense doesn’t get enough attention. It’s getting more than it used to, to be honest. People are talking about it more than they used to.

“(But) he’s had to guard, in many cases, some really good players throughout the playoffs ... he was matched up against all the best guys and he’s done a great job. He’s focused on our record more than his own statistics.

“Sure, he wants to do better, but we’re not worried about it.”

And while both Thompson and the Warriors would have loved for him to break out of his slump sooner than Game 2, in many ways the fact he was still playing so well defensively while struggling so mightily with his shooting stroke was a sign of progress in the mental part of the game.

“I was killing myself the first couple years in the league if I was missing shots,” Thompson said. “It was the end of the world. Now? My teammates have confidence in me, and that’s all I need.”